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GTP or GXP

R

rowekmr

New member
I am looking into getting either to use as a DD and possibly mod for fun. A few years ago I bought a modded Regal GS that was the fastest car I driven but it had small issues that I didn't take the time to sort out and I sold it (regrettably). I always wanted another (doesn't matter the body) and now the prices of the GXP are within my range so I thought of those too. Stock I assume the GXP is faster but with mods I thought the 3800 SC wins. Back when I had the Regal there were plenty of parts online for them but just checking ZZP and Intense websites looks like they provide less parts to mod so was wondering if I should just get the GXP and do intake, exhaust and tune or get another 3800 and do extensive mods. I would like a mid 13 sec car at the least.
What are your ideas?
 


GXP is typically faster stock for stock.

GTP stock doesn't grenade Trannys like a GXP will.

The Money:Gains ratio in a GXP is awful, god awful. Until you spend 4k on a racing Trans and even then, not amazing.

The LS4 is lighter than the 3800SC.

GXP (iirc) has Comp G or better suspension parts factory.

All in all, both are fun, I'm biased towards GXP as I currently Daily one.

If mid 13's is your goal the GXP is almost there stock. Most get 14.1-.3 with the best 1/4 being a 13.6 in perfect conditions. A tune, intake and Exhaust would put you into mid 13's.

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Both will grenade a transmission. GXP's run the transmission way hotter too.

DoD/AFM sucks in those cars as it's the early design that fails more often.
 
I just bought a GXP and really like it. it rides way better than my GTP. the GXP makes about 250 hp at the wheels in stock form, and with a few mods you can get 300 hp at the wheels. I turned off Dod/AFM in the tune so it shouldn't fail as fast as it normally would. with a shift kit and an aftermarket trans cooler the transmission should last longer. my plan for modding to get the 300 hp at the wheels is an overkill tune, an E85/flex fuel kit, upgraded maf sensor, and an LS6 intake manifold swap, and bigger injectors to give the E85 more headroom. all of that will cost about 1200, less if you don't buy the kits from overkill and if you can find a good deal on the LS6 manifold, and you can also do a truck intake manifold for a lot less.

I chose 300 hp at the wheels because that is about how much the transmission can handle and seems to be the happy medium for power per dollar. with a little head work and a cam the LS4 will make 450 hp at the wheels pretty easily.
 
Head work would be pointless, 243's flow stupid good for stock heads.

You won't see 450 wheel hp in that car NA unless it's some redonkculous setup. If your lucky and the tune is good with a okay camshaft that isn't too large for the converter you may be in the mid 300's for power at the tire.

Very simple engines to tune if you understand them.
 


That is on an engine dyno with no loss from a water pump, ac compressor, pulleys , power steering or drivetrain. Factor in all that and it's still in the 350-370hp range.

LS4's are already 10:1 compression, not sure I'd want to mill them anymore before PTV comes into play.
 


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