Document:

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                                                                   EXHIBIT 10.18

                                    AGREEMENT

         THIS AGREEMENT ("Agreement") is being executed and delivered by and
between Emissions Testing, Inc., a Georgia corporation ("the Company") and GCA
Strategic Investment Fund Limited, a Bermuda corporation ("GCA"), and dated as
of December 8, 2000 in order to amend certain agreements between the Company and
GCA and by which the Company and GCA, in consideration of the mutual promises
contained in this Agreement and other good and valuable consideration (the
sufficiency, mutuality and adequacy of which are hereby acknowledged), hereby
agree as follows:

         1. WAIVER OF CERTAIN PROVISIONS. GCA hereby agrees to:

         (i) waive any and all liquidated damages accrued by the Company
pursuant to Sections 10.4(c) and (d) of that certain Securities Purchase
Agreement between the Company and GCA dated June 1, 2000, as amended (the
"Securities Purchase Agreement") up to the date on which the Registration
Statement (as defined in the Securities Purchase Agreement) is declared
effective by the Securities and Exchange Commission (the "Effective Date");

         (ii) waive its right to reduce the Conversion Price as set forth in
Section 10.4(c) of the Securities Purchase Agreement; and

         (iii) waive its mandatory redemption right set forth in Section 10.4(c)
of the Securities Purchase Agreement.

Notwithstanding the foregoing, in the event the Registration Statement is not
declared effective on or before March 1, 2001, all of GCA's rights and remedies
set forth in Section 10.4 of the Securities Purchase Agreement shall be fully
restored and the waivers set forth above shall be of no further effect from such
date and thereafter.

         2. AMENDMENT OF WARRANT EXERCISE PRICE. In consideration of the (i)
waiver granted by GCA set forth in Section 1 hereof, (ii) that certain Agreement
between GCA and the Company dated the date hereof whereby GCA has agreed to
refrain from selling a number of shares of the Company's common stock owned by
it for a period of time defined in such Agreement (the "Lock-Up Agreement"), and
(iii) the consent by GCA to the repayment of a promissory note from Beachside
Commons I, Inc. in the original principal amount of $94,833.35 to the Company
(the "Beachside Loan") through the redemption by the Company of 100,000 shares
of the Company's common stock owned by Porter Lane Investments, Inc. the Company
hereby agrees to amend the exercise price of each warrant listed on EXHIBIT A
hereto issued by the Company to GCA pursuant to the Securities Purchase
Agreement (the "Warrants") from $1.00 to $0.50. In addition, any warrant issued
following the date hereof to GCA pursuant to the Securities Purchase Agreement
shall have an exercise price of $0.50. For the avoidance of doubt, GCA
acknowledges and agrees that by consenting to the transaction described in
clause (iii) of this Section 2, GCA waives any and all breaches, violations and
defaults by the Company under or pursuant to the Securities Purchase Agreement,
resulting directly or indirectly

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from the Company's use of proceeds from the sale of its 7% Convertible Debenture
to fund the Beachside Loan.

         3. AGREEMENT AS TO COMPANY STOCK OPTION PLAN. The Company hereby agrees
that it will not register on a Form S-8 or any other form of registration
statement pursuant to the Securities Act of 1933, as amended, any of the shares
of the Company's common stock reserved for issuance pursuant to the Company's
2000 Stock Option Plan without the prior written consent of GCA.

         4. NO OTHER EFFECT ON THE SECURITIES PURCHASE AGREEMENT OR WARRANTS.
Except as set forth herein, the Securities Purchase Agreement and Warrants are
unchanged hereby and shall remain in full force and effect.

         5. MISCELLANEOUS.

                  (a) CAPTIONS; CERTAIN DEFINITIONS. Titles and captions of or
in this Agreement are inserted only as a matter of convenience and for reference
and in no way define, limit, extend or describe the scope of this Agreement or
the intent of any of its provisions. The parties to this Agreement agree to all
definitions in this statement of the parties to this Agreement. A capitalized
term in this Agreement has the same meaning as it has a capitalized term in the
Securities Purchase Agreement unless the context clearly indicates to the
contrary.

                  (b) CONTROLLING LAW. This Agreement is governed by, and shall
be construed and enforced in accordance with the laws of the State of Georgia
(except the laws of that jurisdiction that would render such choice of laws
ineffective).

                  (c) COUNTERPARTS. This Agreement may be executed in one or
more counterparts (one counterpart reflecting the signatures of all parties),
each of which shall be deemed to be an original, and it shall not be necessary
in making proof of this Agreement or its terms to account for m ore than one of
such counterparts. This Agreement may be executed by each party upon a separate
copy, and one or more execution pages may be detached from a copy of this
Agreement and attached to another copy in order to form one or more
counterparts.

                          SIGNATURES ON FOLLOWING PAGE

                                       2
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DULY EXECUTED and delivered by the Company and GCA, on December 12, 2000,
effective as set forth above.

<TABLE>
<S>                                    <C>
the Company:                           Emissions Testing, Inc.

                                       By: /s/ Rich Parlontieri
                                          ----------------------------------
                                       Title: President & CEO
                                             -------------------------------

GCA:                                   GCA Strategic Investment Fund Limited

                                       By: /s/ Lewis N. Lester
                                          ----------------------------------
                                       Title: Director
                                              ------------------------------

</TABLE>

                                    * * * * *

                                       3

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                                    EXHIBIT A

                             WARRANTS ISSUED TO GCA

1.   Warrant to purchase 250,000 shares of common stock dated as of June 1,
     2000.

2.   Warrant to purchase 50,000 shares of common stock dated as of September 15,
     2000.

3.   Warrant to purchase 50,000 shares of common stock dated as of November 1,
     2000.

4.   Warrant to purchase 50,000 shares of common stock dated as of December 8,
     2000.

                                       4<PAGE>

                                                                   EXHIBIT 10.19

                          GLOBAL CAPITAL ADVISORS, LTD.

                                 October 3, 2000

Mr. William Estroff, President
eMissions Testing, Inc.
104 Colony Park Drive
Suite 600
Cumming, Georgia 30040

     Re:  $100,000 Principal Amount 7% Convertible Debenture of eMissions
          Testing, Inc. dated September 15, 2000

Dear Mr. Estroff:

         This letter confirms that the purchase price for the Convertible
Debenture referenced above (the "Debenture") shall be 100% of the principal
amount of the Debenture rather than 95% of the principal amount of the Debenture
as set forth in that certain Securities Purchase Agreement between GCA Strategic
Investment Fund Limited and eMissions Testing, Inc. All other terms and
conditions of the Securities Purchase Agreement shall remain unchanged for the
closing related to the issuance of the Debenture.

<TABLE>
<S>                                    <C>
                                       Sincerely,

                                       /s/ Lewis N. Lester
                                       -----------------------------------
                                       Lewis N. Lester
                                       Director
                                       GCA Strategic Investment Fund Limited
</TABLE>

LNL/cbc<PAGE>

                                                                   EXHIBIT 10.20

                                                                             GCA
                                                                             ---

                                [GCA LETTERHEAD]

                              December _____, 2000

Richard A. Parlontieri, President
Emissions Testing, Inc.
400 Colony Park
Building 104, Suite 600
Cumming, Georgia  30041

          Re:  Letter Agreement Regarding Transfer Restrictions on Securities to
               be Issued under that certain Securities Purchase Agreement dated
               as of June 1, 2000, between Emissions Testing, Inc., a Georgia
               corporation (the "Company") and GCA Strategic Investment Fund
               Limited, a Bermuda corporation ("GCA"), as amended (the "Purchase
               Agreement") (for purposes hereof, unless otherwise indicated
               herein, all capitalized terms used in this letter shall have the
               same meanings ascribed to them in the Purchase Agreement)

Dear Mr. Parlontieri:

         We refer to the above-referenced Purchase Agreement, pursuant to which,
among other things, the Company agreed to register with the Securities and
Exchange Commission (the "SEC"), for and on behalf of GCA, 2,500,000 shares
(sometimes hereafter referred to as the "Shares") of the Company's common stock,
no par value per share ("Common Stock"), issuable to GCA upon conversion of the
Convertible Debentures and upon exercise of the Warrants.

         GCA understands that the Company has filed a registration statement on
Form S-1 (the "Registration Statement") with the SEC for the registration of
certain shares of the Common Stock in an offering (the "Offering") under the
Securities Act of 1933, as amended (the "Act"). Among the shares of Common Stock
to be registered in the Offering are the Shares.

         Inasmuch as GCA wishes to induce the Company to continue its efforts in
connection with the Offering, GCA hereby agrees with, and represents to, the
Company that GCA will not,

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Emissions Testing, Inc.
December _____, 2000
Page 2

directly or indirectly, sell, offer to sell, grant an option for the sale of,
assign, transfer, pledge, hypothecate or otherwise encumber or dispose of in any
manner, any of the Shares, including pursuant to Rule 144 or Rule 144A under the
Act, from and after the date hereof except as follows:

     (a)  The Company agrees that from and after the date and time that the SEC
          declares the Registration Statement effective under the Act (the
          "Effective Time"), GCA shall be entitled to sell, offer to sell, grant
          an option for the sale of, assign, transfer, pledge, hypothecate or
          otherwise encumber or dispose of in any manner, up to 15% of the
          Shares issuable to GCA upon conversion of the Convertible Debentures
          outstanding as of the Effective Date or issued to GCA thereafter
          pursuant to the Purchase Agreement (the "Conversion Shares"), and 100%
          of the Shares issuable upon exercise of the Warrants owned by GCA as
          of the Effective Date or issued to GCA thereafter pursuant to the
          Purchase Agreement (the "Warrant Shares");

     (b)  The Company further agrees that, from and after the 90th consecutive
          calendar day after the Effective Date, GCA shall have the right to
          sell, offer to sell, grant an option for the sale of, assign,
          transfer, pledge, hypothecate or otherwise encumber or dispose of in
          any manner, up to an additional 15% of the Conversion Shares;

     (c)  The Company further agrees that, from and after the 180th consecutive
          calendar day after the Effective Date, GCA shall have the right to
          sell, offer to sell, grant an option for the sale of, assign,
          transfer, pledge, hypothecate or otherwise encumber or dispose of in
          any manner, up to an additional 20% of the Conversion Shares;

     (d)  The Company further agrees that from and after October 1, 2001, the
          transfer restrictions and limitations set forth herein relating to the
          Shares shall expire and shall have no further force or effect
          whatsoever; and

     (e)  The Company further agrees that notwithstanding the transfer
          restrictions set forth herein, the Company remains fully obligated
          pursuant to the terms and provisions of that certain Registration
          Rights Agreement dated as of June 1, 2000 between the Company and GCA
          (the "Registration Rights Agreement") and such Agreement remains in
          full force and effect without any amendment.

     GCA agrees and understands that:

     (f)  Any sale or other transaction involving all or any part of the Shares
          are, and shall hereafter remain, subject to all applicable federal and
          state securities laws and regulations.

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Emissions Testing, Inc.
December 12, 2000
Page 3

     (g)  The Company may place a legend reflecting this letter and terms hereof
          on any certificate evidencing the Shares which are subject to the
          restrictions set forth above at the time of their issuance, and may
          give written notice of this letter, and the terms hereof, to the
          Company's transfer agent;

     (h)  This letter, and the terms hereof, shall be binding upon GCA and its
          successors and assigns; and

     (i)  The Company is relying upon the agreements and representations of GCA
          set forth in this letter in filing the Registration Statement and
          amendments thereto and in consummating the Offering.

     (j)  The Company shall not amend or terminate in any manner whatsoever any
          agreement relating to the restriction of the transfer of shares of the
          Company's Common Stock, as described in the Registration Statement and
          attached as exhibits thereto, without the prior written consent of
          GCA.

         In the event the Registration Statement has not been declared effective
by the SEC on or before November 1, 2001, GCA and the Company hereby agree that
this Agreement shall terminate automatically without any further action required
by GCA or the Company and GCA shall have all of the rights set forth in the
Purchase Agreement, the Registration Rights Agreement and any related
transaction agreement. If the foregoing meets with your understanding of our
agreement, please so signify by signing and returning this Letter Agreement to
us.

<TABLE>
<S>                              <C>
                                 Very truly yours,

                                 GCA STRATEGIC INVESTMENT FUND
                                 LIMITED

                                 By: /s/ Lewis N. Lester
                                    --------------------------------------
                                   Name: Lewis N. Lester
                                        ----------------------------------
                                    Position: Director
                                             -----------------------------
</TABLE>

<PAGE>

Emissions Testing, Inc.
December 1, 2000
Page 4

Agreed to and accepted as of the day and year first above written.

EMISSIONS TESTING, INC.

By: /s/ Rich Parlontieri
    ------------------------------
   Name: Rich Parlontieri
         -------------------------
   Position: President/CEO
            ----------------------

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