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                                                                   EXHIBIT 10.28


                                                                             ARM




                                December 1, 2000



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

          Re:  Letter Agreement Regarding 100,000 Shares of the Common Stock of
               Emissions Testing, Inc., a Georgia Corporation (the "Company"),
               Owned of Record by ARM & Associates, LLC ("ARM")

Dear Mr. Parlontieri:

     As you know, ARM is the owner of record of 100,000 shares of the common
stock, no par value per share, of the Company.

     The Company has filed a registration statement on Form S-1 (the
"Registration Statement") with the Securities and Exchange Commission (the
"SEC") for the registration of certain shares of the Company's common stock
("Common Stock"), in a public 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 100,000 shares of Common Stock owned of record by
ARM (the "Registered Shares").

     Inasmuch as ARM wishes to induce the Company to continue its efforts in
connection with the Offering, ARM hereby agrees with, and represents to, the
Company that ARM will not, 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 Registered Shares (or any
interest therein), INCLUDING, WITHOUT LIMITATION, PURSUANT TO RULE 144 OR RULE
144A UNDER THE ACT, from and after the date hereof except as follows: The
Company further agrees that ARM shall have the right to sell, offer to sell,
grant an option for the sale of, assign, transfer, pledge, hypothecate or
otherwise encumber and/or dispose of in any manner, all or any part of the
Registered Shares at any time after the earlier of (I) 12:01 AM (Atlanta,
Georgia time) on October 1, 2001, or (II) the date and time that the Company has
reduced to $250,000 or below the outstanding aggregate principal amount of the
Company's indebtedness to GCA Strategic Investment Fund Limited, a Bermuda
corporation ("GCA") (or its assignees) under the convertible debentures issued
and sold (before or after the date hereof) by the Company pursuant

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Emissions Testing, Inc.
December 1, 2000
Page 2


to the terms of that certain Securities Purchase Agreement dated effective as of
June 1, 2000 between the Company and GCA, as the same may be amended from time
to time.

     ARM agrees and understands that:

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

          (b)  The Company may place a legend reflecting this letter and terms
               hereof on any certificate evidencing all or any part of the
               shares described herein, and may give written notice of this
               letter, and the terms hereof, to the Company's transfer agent;

          (c)  This letter, and the terms hereof, shall be binding upon ARM and
               the successors and assigns of ARM; and

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

     The Company agrees that, upon the occurrence of the event described in
clause (II) above, the Company shall give prompt written notice thereof to ARM
at the last known address then available to the Company.

     The parties hereto agree that this Letter Agreement shall not be amended,
modified or terminated without the prior written consent of GCA, which consent
may be granted or denied in the sole discretion of GCA.

     If the foregoing meets with your understanding of our agreement, please so
signify by signing and returning this Letter Agreement to us.

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<S>                                    <C>
                                       Very truly yours,

                                       ARM & ASSOCIATES, LLC



                                       By: /s/ A. R. Marshall
                                          ------------------------------------
                                        Name: A. R. Marshall
                                             ---------------------------------
                                         Position: General Partner
                                                  ----------------------------
</TABLE>

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Emissions Testing, Inc.
December 1, 2000
Page 3


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
            ----------------------