Thread: Best gains for dropping $2000 into a GTP

To whoever said a supercharged setup will never make more power than a turbo setup...friend of mine had his Gen V setup running very low 10s before he demodded and bought something else.

Originally Posted by BwolfGT

To whoever said a supercharged setup will never make more power than a turbo setup...friend of mine had his Gen V setup running very low 10s before he demodded and bought something else.

demanding video

Originally Posted by 99prixgt

demanding video

I can ask him for a track slip, his car was insane though. He demodded and sold though I think he bought a fiero or a camaro and he's gonna turbo it.

Originally Posted by 01GTP

no need for a cat back or fuel pump rewire.

there is a huge need for a catback...sorry but the 2.25" catback just doesnt flow enough from the factory...ESPECIALLy on a pullied car...a catback can drop a couple tenths of a second in the 1/4 mile on a STOCK gtp...let alone a pullied one. As far as the fuel pump rewire. It can be argued...but i would say its definitely worth the $30. Friend of mine was having consistency issues with his L67 at the track until he got the fuel pump rewire...problem solved.

Originally Posted by MitchieGTP

there is a huge need for a catback...sorry but the 2.25" catback just doesnt flow enough from the factory...ESPECIALLy on a pullied car...a catback can drop a couple tenths of a second in the 1/4 mile on a STOCK gtp...let alone a pullied one. As far as the fuel pump rewire. It can be argued...but i would say its definitely worth the $30. Friend of mine was having consistency issues with his L67 at the track until he got the fuel pump rewire...problem solved.

Lmao. Sorry dude but the stock catback on these things has been proven to flow fine up to about 300 at the wheels. Header's through cat is about all that matters on these cars.

ya i hope that was a joke, the catback having no flow issues until 350WHP or about 400 at the crank is stated on just about every exhaust thread

Originally Posted by MitchieGTP

there is a huge need for a catback...sorry but the 2.25" catback just doesnt flow enough from the factory...ESPECIALLy on a pullied car...a catback can drop a couple tenths of a second in the 1/4 mile on a STOCK gtp...let alone a pullied one. As far as the fuel pump rewire. It can be argued...but i would say its definitely worth the $30. Friend of mine was having consistency issues with his L67 at the track until he got the fuel pump rewire...problem solved.

lol...wut?

Yeah a guy wanted to buy my catback just for the flow for his new pulley, I was like dude just get headers, worry about the catback when you're running 10s.

uhhh...no it wasn't a joke...put a stock gtp up against one that has a mandrel bent 2.5" system and see what happens. I don't see how theres an argument here. A 2.25" system flowing as good as a mandrel bent 2.5" or 3" system? I think not. I regret not putting a cat back on my GTP because the guys that Ive talked to at the track all said they had great gains up top from their after market cat backs on cars with just basic bolt ons...nowhere near 400hp.

they aren't any where near 400hp because they wasted their money on a catback instead of adding actual horsepower. im just saying the stock catback has been dyno tested to be unrestrictive, dyno sheets dont lie

i bet you gained 2 hp from that catback. butt dyno unapproved.

Originally Posted by MitchieGTP

uhhh...no it wasn't a joke...put a stock gtp up against one that has a mandrel bent 2.5" system and see what happens. I don't see how theres an argument here. A 2.25" system flowing as good as a mandrel bent 2.5" or 3" system? I think not. I regret not putting a cat back on my GTP because the guys that Ive talked to at the track all said they had great gains up top from their after market cat backs on cars with just basic bolt ons...nowhere near 400hp.

L

O

L

Fail. It's a joke...and whoever taught you...is a joke too...so if it was yourself where you learned all of this "info"...TRY READING AROUND HERE MORE. You'll see why.

Originally Posted by MitchieGTP

intake, headers, 3.4 pulley, 3" or 2.5" catback, custom tune, fuel pump rewire...basic bolt ons. Then you will have some money left over to rebuild the transmission and have a car that runs mid-low 13s reliably.

LOLWUT?

Originally Posted by MitchieGTP

uhhh...no it wasn't a joke...put a stock gtp up against one that has a mandrel bent 2.5" system and see what happens. I don't see how theres an argument here. A 2.25" system flowing as good as a mandrel bent 2.5" or 3" system? I think not. I regret not putting a cat back on my GTP because the guys that Ive talked to at the track all said they had great gains up top from their after market cat backs on cars with just basic bolt ons...nowhere near 400hp.

Is this because they have different cars? Many cars will respond to a cat back...ours do not. Unless of course you're in the 400whp range. Good luck making 400whp with:

Originally Posted by MitchieGTP

intake, headers, 3.4 pulley, 3" or 2.5" catback, custom tune, fuel pump rewire...basic bolt ons.

Yup. Some cars get woken up by a catback, ours just like headers.

That is because the manifolds and downpipe are the restrictive part, not the catback. And I bet if you put a stock GTP against one with a "high performance" exhaust system. One will sound different and they will run the same exact times. You really can't justify putting a catback on your car and gaining horsepower...hell, Paul @ PRJ ran a Whipple with a stock catback...and still made great numbers...also...Vogel used a stock F-Body muffler and stock sized piping...like 2.25" IIRC and that thing was an 11 second car. What your failing to realize is that these cars don't have restrictive exhaust systems after the converter...minus the U-Bend...which does need removing. The weak point is the manifolds and DP...like I said earlier...that's where you will make power.

i still dont see how this can be argued. Maybe if you had dyno numbers from an 11 second car proving that a bigger cat back did nothing for it, but I can guarantee there is some power being lost in a 2.25" catback on a 3.8L with a blower (let alone an 11 second one). No doubt it made great numbers...but could it have made better numbers with a bigger mandrel bent exhaust?? I know that a lot of power is lost at the manifold and downpipe....thats why when i put a pulley on my gtp i used a powerlog and 3" r/t downpipe...but I'm definitely regretting not putting on a catback.


realdiehl...as far as your "LOLWUT?" comment..im not too sure what ur asking. And the guys at the track that I talked to that said they had good gains from their cat backs were w-body guys (either regal gs or gtp).

Originally Posted by MitchieGTP

i still dont see how this can be argued. Maybe if you had dyno numbers from an 11 second car proving that a bigger cat back did nothing for it, but I can guarantee there is some power being lost in a 2.25" catback on a 3.8L with a blower (let alone an 11 second one). No doubt it made great numbers...but could it have made better numbers with a bigger mandrel bent exhaust?? I know that a lot of power is lost at the manifold and downpipe....thats why when i put a pulley on my gtp i used a powerlog and 3" r/t downpipe...but I'm definitely regretting not putting on a catback.


realdiehl...as far as your "LOLWUT?" comment..im not too sure what ur asking. And the guys at the track that I talked to that said they had good gains from their cat backs were w-body guys (either regal gs or gtp).

That's just how these things are, I'm getting rid of my catback soon for a new stocker, I'll see if I actually loose any power.

Originally Posted by MitchieGTP

i still dont see how this can be argued. Maybe if you had dyno numbers from an 11 second car proving that a bigger cat back did nothing for it, but I can guarantee there is some power being lost in a 2.25" catback on a 3.8L with a blower (let alone an 11 second one). No doubt it made great numbers...but could it have made better numbers with a bigger mandrel bent exhaust?? I know that a lot of power is lost at the manifold and downpipe....thats why when i put a pulley on my gtp i used a powerlog and 3" r/t downpipe...but I'm definitely regretting not putting on a catback.


realdiehl...as far as your "LOLWUT?" comment..im not too sure what ur asking. And the guys at the track that I talked to that said they had good gains from their cat backs were w-body guys (either regal gs or gtp).

look, let me clear this up for you. its not that you wont make more power, its that youll not make enough power from it to justify the cost of replacing it. regardless of how heavily you are modded, dropping the cat back or going bigger is worth 5-7 whp max, which most people cant even tell the difference between.

there, ended that argument. this is why we say it is a waste to change out anything in the catback unless youre knocking on mid 12s or faster with your car (~300whp +).

Originally Posted by Poil336

i've taken college courses on stuff. i must be a god.

you can never stop learning. ever. high school was a joke and, so far, college is a joke. i've picked up more useful info from this website than the last 5 years of my life. anybody that's new here and asks for opinions on modding is welcome to try their own way but ****ing respect the people that have torn these cars down to the ground and built them again and listen to what they have to offer.

anyways, back to cars, Bwolf, where's this timeslip?

Well I've actually been hoping nothing's happened to the guy, no one's been able to get a hold of him for a couple weeks an he hasn't been around his house at all. So if all goes well I'll ask him for a copy of the time slip.