I'm asking this becasue from what i hear 3 in. exhaust is the only way to go...but i am skeptical because my car is stock right now, and even after the exhaust i only plan to do the open element and possibly chip it. Overall i doubt it'd ever push more than 180-185 HP at the crank. So my question is whether 3 in. exhaust would even be beneficial to my car at all, or is a 2 1/2 inch exhaust setup the better route for me to go.

Any input would be greatly appricaited (and thanks to all the guys who helped me in my open element topic!!)...

PS: Incase it matters, I'm either going to get the Dynomax Ultra Flo cat-back (2 1/2 inch intermediate), or the Edelbrock RPM series cat-back (3 inch intermediate), depending on what would be better for my car.

 

A 2.5" is more than adequte for what you have planned. A single 2.5" will support well over 230 at the wheels. A 3" would be fine as well but since you aren't going crazy on the mods you would be really be happy with either. If anything, your low RPM scavaging will be great and will give you a great feeling of

 

go with 3" diff is ngiht and day. also get a good high flow Y pipe world of diff

 

Any other opinions?? I'm still kinda undecided because i keep hearing 2 different sides of the story...

 

I would go 3" with 1 5/8" headers.

After many many many dyno sessions with many diffrent cars, and diffrent combo's, opening up the exaust, has made more power on every one of them, from my L03, to 500hp small blocks, to some crazy big-blocks. Everyone of these V8's has plenty of off idle torque, to cause traction issues, go with the larger exaust, and pick up the HP in the rev range that you use most of time (other than launching, you are about 3k the rest of the 1/4 mile).

 

I have a complete unrestricted 2.5 now and it flows pretty damn good for a L03, but I only chose it because of price.

 

go 3inch. 2.5 is fine if you don't ever want to make any more power than stock. the 3inch will be a very healthy upgrade for stock, making as much poower as teh 2.5 and still leave you room to grow. teh larger diameter tubing also lends itself to a better exhaust note.

later
tim

 

i'm not on the bigger is better bandwagon. Your engine as stock as it sounds, will always make more torque than horsepower, and with stock gearing I would think that an extra 5 ftlb of low end torque in the higher gears would make for a more exciting ride than would 3 hp up top. I mean, since the motor is making mostly torque anyway, play to the motor's strength, rather than try to make it somthing its not by trying to add top end. Just my .02 though.

 

and i am not SURE about this, but I have heard that a good exhaust tone is a matter of proper velocity going into the muffler. If you think about it, the pressure difference in the exhaust, pre muffler might also affect scavenging, as well as sound quality. If I am wrong correct me here on this reasoning.

in a 3" pipe going into the muffler, the exhaust gasses are not under as much pressure as they would be running through 2 inch pipes. This affects velocity. Then, look at it this way. The pressure difference between the muffler (low pressure due to volume) and the exhaust (high pressure) affects scavenging. If the exhaust going in is of higher pressure, the low pressure of the muffler would have more pull on the gasses due to the greater difference in pressure. It seems that with a lower pressure exhaust charge the scavenging affect is lessened. Kind of like a turbo system. you want a downpipe that keeps velocity high, and an after turbo exhaust that is as big as possible, because you want the gasses to be sucked past the turbo quickly to help it spool faster.

 

Yea guys...i've decided to go 2 1/2 on this one. I appriciate all of your help, but ultimately it was oddoylerules who pushed it over the top. I just need to find the best place to get the Dynomax Ultra Flo cat-bac from and then i'll order it.


EDIT: If anyone knows of a place that sells the exhaust cheaper than Summit, please let me know!!!

 

Don't event hink of going anything other than 3" - its a move that will pay dividends later on.

 

Did anyone other than Shifty read that he's ONLY going to do an open element and possibly a chip?