I did a search for 12" brake upgrade for all four corners and is the only brake system that works for the rears the GXP brakes?

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2003 Grand Prix SE / Redfire Metallic
GT/GTP body conversion - 3"FWI - 56mm TB - AGX/SSC combo - 077's - GMPP front & rear sway bars

Bear has a setup as well but pretty much yeah, the GXP is the only stock setup that will fit.

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2008 Greater Ohio Club Grand Prix President

My Mod List

thats what i thought. I guess I will keep the rears 11" then
Thanks

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2003 Grand Prix SE / Redfire Metallic
GT/GTP body conversion - 3"FWI - 56mm TB - AGX/SSC combo - 077's - GMPP front & rear sway bars

Not sure how much youd want to pay for a rear setup but Wbody store has a rear 12" brake upgrade (Im almost positive is the GXP setup) for 600 + shipping. Comes with everything accept lines. If you look through car-parts.com you should be able to find a rear setup or front and rear setup used for cheaper than the new too. (I went through car-parts and it was cheaper shipped for the whole setup used than for just the rear new)

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Mods: Powder coated ported exhaust manifolds/ Powder coated 3" down pipe/ Intense PCM/ 3.4 press on pulley/Trasher Intake/ Fuel pump rewire/AL 103 plugs/ Alternator voltage boost/ 6000k HID kit/

Should I select this option for the rears on there website? -> w/traction control (opt NW7)

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2003 Grand Prix SE / Redfire Metallic
GT/GTP body conversion - 3"FWI - 56mm TB - AGX/SSC combo - 077's - GMPP front & rear sway bars

Actually what i did was check the front GXP calipers and called most places with a front listed and asked if they had the rear setup because i found no listings for the rear only.

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Mods: Powder coated ported exhaust manifolds/ Powder coated 3" down pipe/ Intense PCM/ 3.4 press on pulley/Trasher Intake/ Fuel pump rewire/AL 103 plugs/ Alternator voltage boost/ 6000k HID kit/

I called a local yard and they said the GXP and Buick Lacross share the same rear caliper. So is this true? Will the buick rear bolt up then?

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2003 Grand Prix SE / Redfire Metallic
GT/GTP body conversion - 3"FWI - 56mm TB - AGX/SSC combo - 077's - GMPP front & rear sway bars

Im actually not sure about that. Both parts. Someone that has a little more knowledge on this part might want to chime in. If all else fails I guess you could always call up a dealership to see what the difference between the calipers is.

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Mods: Powder coated ported exhaust manifolds/ Powder coated 3" down pipe/ Intense PCM/ 3.4 press on pulley/Trasher Intake/ Fuel pump rewire/AL 103 plugs/ Alternator voltage boost/ 6000k HID kit/

That could be some very good information. Also, where do you guys find GXP parts? I cannot find any information anywhere on anything GXP pre-2004.

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2000 NavyBlueMetallic GTP Coupe 14.007 @98.5 - New time coming soon!
HPTuners / Intercooler / 1.8 SLP Rockers / 3.1" / 180° / TB Shield / FWI / PLOG / Jimmy-C Downpipe / U-Bend Delete / Mark VIII Fan / Alt. rewire / FP rewire / F-Body Brakes / Buick Strut Braces / SLP Tips / 20% Tint

That is because the GXP's didnt start production till 2004 badged as a 2005 model until till current I do believe. The pickens at junk yards are going to be slim at best.

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James Shafer 2003 GP GTX St. Louis MO
Mods: 1.9 Modified Rockers, TOGs w/ SLP Cat, Brisk LSG Plugs, 180 Tstat, PRJ 10.4 Plug Wires, P/P Gen 3, Ported L67 TB, SLP Ram Air Hood/Airbox, 2.5" Catback, 3.5 Pulley, Gen 1 Spoiler, ZZP Poly mounts, RAT Dogbones, 18" TSW Mondellos