Currently running

3' catless dp
60lbs Inject
2.8 Pulley
basic tune

Will be running Injen Intake as well, Now as far as my Furture mods i MIGHT drop to a 2.7 with a H/E as well, So with that being in mind Which would be better? i have heard 3' but i have also heard those are bad on our cars, Now my thinking is that on a NA car 2.5 is GREAT, But since we have F/I car wouldnt 3inch be better since your flowing much more air?

talk

 

i think you'll be alright with a 3"

 

2.25 is great for NA
2.5 up to 300hp
3 above that

 

i thought so to, and plus with have a 3' Catless DP wouldnt that bottleneck the system

 

Stay with a 2.5 if you're only going to be doing a 2.8. Get an aftermarket header/dp and an over-axle-back.

 

you're source???

 

Run a 3inch exhaust.

 

search

The stock 2.5 exhaust flows well up until 300 hp, only bottlenecks are in the dp and axle back.

 

A 3inch exhaust will lower your boost which is GOOD. Remember, boost does not equal power, and to much boost can be a bad thing.

Take it from someone who is running 3inch exhaust and putting down over 325whp on the stock m62, run a 3inch exhaust, you won't regret it!

 

It basically depends on where you want to go from here... you could probably get away with a 2.5 catless If you wanted to... i would go 3 inch would probably be ideal though... you wont make that much power unless your running N2O but i think you will be happy with the results

Zach06cobaltsc is the 325WHP on your 50 shot?

 

See i dont "wanna just get away" I want a good flowing system that doesnt sound overly bad as well and flow with no issues, If i run lower boost who cares. i want the stock stuff No if ands or buts about it, Its good for what it is, But not what i want.

 

Dont blame you go 3 and i think you will be satisfied

 

im gonna be running a 3" vortex header with 3 inch downpipe and 3 inch exhaust. is it going to be louder then the legal limit?

 

oh and i would do headers and catless dp but thats up to you...

sorry posted before i saw yours sounds good but as for the legal limit i dont know sorry bud good luck

 

already have the catless DP....

 

http://www.youtube.com/watch?v=_paE9sjjbzk

http://www.youtube.com/watch?v=6AQReF_T7Uo

oh yeah

 

why do you think i bought this setup lol,

if i put a silencer in my muffler, will it quiet it down enough?

does anyone have information on silencer's for this setup???

 

Yes, it is.

Yes, a 3" will allow allow for better flow, but at a slower velocity.

The faster the exhaust comes out, the better...

Someone with a 3" setup, and a cold air, who had a 3" exhaust, dyno'd 8 - 10 more when he switched over to his 2.5"... he did this on the same day, not at different times or anything.. a good solid before and after test.

the 300 mark isnt set it stone, it just just a good place mark of where the 3" would start being more beneficial than a 2.5". I think that number should be a wee bit lower, around 270 or 280... but thats all up to you.

 

so your saying i should have a 2.5 inch muffler? instead of a 3?

 

make sure you dont confuse muffler with catback.

Id stick with a 2.5 if i were you.

 

just because you're putting down a certain hp # doesn't mean it's the best setup. plus, you hp #'s put you in a different category.

3" will be too big. stick with the 2.5". on a 3" you will lose some velocity especially with the bigger downpipe.

 

reall/, so injen cai, 3 inch downpipe vortex header, 2.5 inch catback, is the best setup with ottp stage 1 meth injection 60/40 tuned mix, tb, h/e, dual pass endplate? are you sure?

 

yes... if you are planning to go faster (smaller pulley, things like that)... id do a 3" so you dont have to buy twice, but it would be a less kick in the pants until then.

 

well im in a conastant debate over 2.7/ 2.8. the way i drive i think the 2.7 will be just as reliable with the cooling mows i'll buy, but i would have to get a custom tune, i'll be better off with a 2.8, whats the difference anyway 5whp?

 

the difference is how much harder the pull will be... youll be fine with a 2.7... promise.

plus it will be that much more fun.