Umm, if you are saying that you will get paid $625 and it will be $825 for the GT Bumper and therefore $200 difference, then DO NOT DO IT. $825 is a TOTAL RIPOFF. Get a GT one off of bumpers.com for like $2xx and have it installed for $50 or less and POCKET the difference. MAKE $300 instead of spend. Also, I had my duals custom installed ('94 Cobra Exhaust Take-offs) AND a new GT bumper painted and installed... ALL for $500, so even 625 seems like a ripoff.
Part of the difference is that you probably need the thing UNDER the bumper skin too, but that should not cost you $500 over the bumpers.com route.
Hopefully this whole thing made sense and can help you make a knowledgable decision. Yes, you should get the GT Bumper, but if I read correctly and it will cost $825, that is not a good deal. Another thing is, a GT bumper is not $200 more than a V6 bumper, its just two holes that make the difference. Something's fishy.