hp is still calculated from torque.
even at high rpm, more tq is still good.
in fact, its even better than low end torque, because past 5252, every ft/lb of torque becomes worth more and more HP.

 

So what i am i going to be looking at a nice flowing 2.5 magnaflow catback? i just don't want to cut the car short, i have plans for the car and im shooting for 330whp on the eaton with no juice.

 

Thats correct, which is what I was agreeing with sick06cobalt with, he posted on the first page that with a turbo'ed car, you can gain "x" amount of hp with a 3 or 3.5 exhaust, but with a SC car, those sizes would hurt your performance. So there is no comparison between a SC and Turbo'ed car running a 3" exhaust, the turbo will make way more power with it.

 

yup agreed.

i just hope we get someone who dynos both and shows some proof of the differences

 

That would be ideal, then all the arguing can stop haha.

 

i think i may go 2.5 custom then and keep some of this tq

 

can people give me some of their opinions on the GMPP exhausts? I think I want to get that along with a header/dp combo (maybe vibrant), stage 2, 2.9 pulley, and a tune afterward... Would it be more beneficial to get a different exhaust, or is it fine for what im looking for? an0malous, i know your running that cat back and have very good times.

 

I ran the GMPP catback and loved it, never had a problem with it and it sounded great. For your planned setup it would be perfectly fine.

 

it is still 2.25 " piping but a better flowing muffler i think it would be a nice fit for the car

 

What kind of power did you make when you had your ss? What mods too? Thanks.

 

I made 271whp/260 wtq. Mods included: 2.6 pulley, 60 lb injectors, intake, full exhaust (header/dp/catback), Cobra H/E, Motor/Tranny Mounts.

 

so with my 2.5 inch corsa exhaust and my turbocharger im making 244wtq. If I put one of those electronic cutout things on and dynoed again, you think I would gain horsepower by using that and still be able to cruise on my 2.5 inch for daily driving sound control. Also, would adding a cutout mess with my tune alot when I use it since the car is stuned on a 2.5 inch exhaust.?

 

I had no noticable bottom end loss with 3" exhaust, and very noticable top end gain.

 

are you sure thats what it was or perhaps was it just your powerband being shifted up

 

If the powerband shifted up, then power would be lost in the low rpm area. For the most part, exhaust doesn't shift the powerband very much. Adjusting cam timing will dramatically change it, but not exhaust.

 

interesting, im stuck between 2.5 and 3.0 im leaning towards 3.0 now though any other input

 

Go with 3". It sounds better, and if anything else it leaves room for more mods. I'm using my exhaust from when I blew it up, for my new build, and with nitrous I'll be close to 500 whp, so the exhaust I have should be fine, considering its all straight through mufflers, and mandrel bent.

 

yeah i think im done around 330 whp or so unless i decide to spray it

 

Whats done to your ****?

 

2.5 pullied
dual pass endplate option b
dual pass h/e
cti lt header
cti 3" catless dp
stock catback
hpt tuned
hurst sts
stg2 axles
stg4 full ceramic clutch
tranny mounts
cab's
lots of little crap

Its in storage now so here comes what is being added well it sleeps

meth inj
rebel 3" cai
ported ls4 tb
ported blower
ported intake manifold
3" catback
ported head ( 5 angle valve job) .0010 mill
1mm bigger valves
9.5:1 forged pistons
cometic gasket
arp headstuds

thats all for now depending on how the tvs blower does

 

Hm, this is an interesting topic that also ahs me torn. As most of you know, I am stock, and I am not one to waste money really. If I was to get need a 3 inch exhaust later. I'd think it more sensible to buy the 3 inch first so you wouldn't have to buy it later.

But if a 2.5 could work well when you're over 300whp I would keep it. And would a 3"-2.5" header DP help with this also?

 

Right this second, I'd say your around 280ish whp. Stock cat-back = shitty

However, once you get it out of storage I'd say, 320-330 whp, ported head makes a HUGE difference in this motor, and cams would make and even huger difference.

 

all of this talk about low end loss.

you do realize you can make up for this by tweaking the map in your favor?


i do have a 3 inch exhaust on my car. do i have another car with the exact same mods to compare to? nope.

do i care? nope.

 

im not sure if i want the cams yet driveabilty is nice to have

yes teach me the way

I figured thats what im around to the car is trapping 107+ when im on and off the gas so it has some go to it

 

Same here. It really picks up more at the top. Also, it sounds great. I don't like many of the other companies, but hahn's is nice and deep. It isn't even loud really until 4k, but I have no cat either. As soon as I finish some more work, I'll get a new dyno and see exactly how it impacted things for me.