Exhibit 10.25

JOINDER TO AMENDED AND RESTATED CREDIT AGREEMENT

THIS JOINDER TO AMENDED AND RESTATED CREDIT AGREEMENT (this “Joinder”) is
entered into as of November 2, 2015, by and among the lenders identified on the
signature pages hereof (each of such lenders, together with its respective
successors and permitted assigns, is referred to hereinafter as a “Lender” and
collectively as the “Lenders”), WELLS FARGO BANK, NATIONAL ASSOCIATION, a
national banking association, as administrative agent for each member of the
Lender Group and the Bank Product Providers (in such capacity, together with its
successors and assigns in such capacity, “Agent”), POWER SOLUTIONS
INTERNATIONAL, INC., a Delaware corporation (“Parent”), PROFESSIONAL POWER
PRODUCTS, INC., an Illinois corporation (“PPPI”; Parent and PPPI, are referred
to hereinafter each individually as a “Original Borrower”, and individually and
collectively, jointly and severally, as the “Original Borrowers”), POWERTRAIN
INTEGRATION ACQUISITION, LLC, an Illinois limited liability company (“PI
Acquisition”) and BI-PHASE TECHNOLOGIES, LLC, a Minnesota limited liability
company (“Bi-Phase”; together with PI Acquisition, the “New Borrowers” and each,
individually, a “New Borrower”).

WHEREAS, the Original Borrowers, Agent, and Lenders are parties to that certain
Amended and Restated Credit Agreement dated as of April 1, 2014 (as amended,
restated, supplemented or otherwise modified from time to time, the “Credit
Agreement”);

WHEREAS, Parent has formed PI Acquisition and Bi-Phase, two new wholly-owned
subsidiaries; and

WHEREAS, pursuant to Section 5.11 of the Credit Agreement, certain Wholly-owned
Subsidiaries of the Loan Parties must execute and deliver certain Loan Documents
to Agent, and the joinder to the Credit Agreement by the undersigned New
Borrowers may be accomplished by the execution of this Joinder in favor of
Agent, for the benefit of the Lender Group and the Bank Product Providers.

NOW THEREFORE, in consideration of the premises and mutual agreements herein
contained, the parties hereto agree as follows:

1.    Defined Terms. Unless otherwise defined herein, capitalized terms used
herein shall have the meanings ascribed to such terms in the Credit Agreement.

2.    Joinder. In accordance with Section 5.11 of the Credit Agreement, each of
the New Borrowers is hereby joined to the Credit Agreement as a Borrower with
the same force and effect as if originally named therein as a “Borrower”, and
each of the Borrowers hereby (i) agrees to be bound by the terms and conditions
of the Credit Agreement applicable to it as a “Borrower”, (b) is a party as a
Borrower under the Credit Agreement, in each case as if such New Borrower were a
direct signatory thereto and (c) represents and warrants that the
representations and warranties made by it as a “Borrower” thereunder are true
and correct in all material respects (except that such materiality qualifier
shall not be applicable to any representations and warranties that are already
qualified or modified by materiality in the text thereof) on and as of the date
hereof. In furtherance of the preceding sentence, without limiting

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any provision of any Loan Document to which each of the New Borrowers is now
becoming a party as a Borrower, and in accordance with the terms of the Loan
Documents, each of the New Borrowers agrees to be jointly and severally liable
with the Original Borrowers for all Obligations.

3.    Schedules. Schedules 4.1(b), 4.1(c), 4.11 and 4.24 attached hereto amend
and restate Schedules 4.1(b), 4.1(c), 4.11 and 4.24 to the Credit Agreement and
shall be deemed a part thereof for all purposes of the Credit Agreement.

4.    Continuing Effect. Except as expressly set forth in Section 2 or 3 of this
Joinder, nothing in this Joinder shall constitute a modification or alteration
of the terms, conditions or covenants of the Credit Agreement or any other Loan
Document, or a waiver of any other terms or provisions thereof, and the Credit
Agreement and the other Loan Documents shall remain unchanged and shall continue
in full force and effect, in each case as amended hereby. Except as specifically
provided herein, Agent and each Lender hereby reserves and preserves all of its
rights and remedies against any Loan Party under the Credit Agreement and the
Loan Documents.

5.    Reaffirmation and Confirmation; Covenant. Each of the New Borrowers
represents and warrants to Agent, the Lender Group and the Bank Product
Providers that this Joinder has been duly executed and delivered by such New
Borrower and constitutes its legal, valid, and binding obligation, enforceable
against it in accordance with its terms, except as enforceability thereof may be
limited by bankruptcy, insolvency, reorganization, fraudulent transfer,
moratorium, or other similar laws affecting creditors’ rights generally and
general principles of equity (regardless of whether such enforceability is
considered in a proceeding at law or in equity). Each Loan Party party hereto
hereby agrees that this Joinder in no way acts as a release or relinquishment of
the Liens and rights securing payments of the Obligations. The Liens and rights
securing payment of the Obligations are hereby ratified and confirmed by each
Loan Party party hereto in all respects.

6.    Effectiveness. This Joinder shall become effective upon the execution and
delivery hereof by the parties hereto.

7.    Miscellaneous.

(a)    THIS JOINDER SHALL BE SUBJECT TO THE PROVISIONS REGARDING CHOICE OF LAW
AND VENUE, JURY TRIAL WAIVER, AND JUDICIAL REFERENCE SET FORTH IN SECTION 12 OF
THE CREDIT AGREEMENT, AND SUCH PROVISIONS ARE INCORPORATED HEREIN BY THIS
REFERENCE, MUTATIS MUTANDIS.

(b)    Counterparts. This Joinder may be executed in any number of counterparts
and by different parties on separate counterparts, each of which, when executed
and delivered, shall be deemed to be an original, and all of which, when taken
together, shall constitute but one and the same Joinder. Delivery of an executed
counterpart of this Joinder by telefacsimile or other electronic method of
transmission shall be equally as effective as delivery of an original executed
counterpart of this Joinder. Any party delivering an executed counterpart

 

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of this Joinder by telefacsimile or other electronic method of transmission also
shall deliver an original executed counterpart of this Joinder but the failure
to deliver an original executed counterpart shall not affect the validity,
enforceability, and binding effect of this Joinder.

(c)    Loan Documents. This Joinder shall constitute a Loan Document.

[signature pages follow]

 

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IN WITNESS WHEREOF, the parties hereto have caused this Joinder to be executed
and delivered as of the date first above written.

 

ORIGINAL BORROWERS:     POWER SOLUTIONS INTERNATIONAL, INC., a Delaware
corporation     By:   /s/ Michael P. Lewis     Name:   Michael P. Lewis    
Title:   Chief Financial Officer

 

    PROFESSIONAL POWER PRODUCTS, INC., an Illinois corporation     By:   /s/
Michael P. Lewis     Name:   Michael P. Lewis     Title:   Chief Financial
Officer

 

NEW BORROWERS:     POWERTRAIN INTEGRATION ACQUISITION, LLC, an Illinois limited
liability company     By:   /s/ Michael P. Lewis     Name:   Michael P. Lewis  
  Title:   Chief Financial Officer

 

    BI-PHASE TECHNOLOGIES, LLC, a Minnesota limited liability company     By:  
/s/ Michael P. Lewis     Name:   Michael P. Lewis     Title:   Chief Financial
Officer

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    WELLS FARGO BANK, NATIONAL ASSOCIATION, as Agent, as Lead Arranger, as Book
Runner, and as a Lender     By:   /s/ Brian Hynds     Name:   Brian Hynds    
Title:   Vice President