View Full Version : Exhaust question

03-01-2005, 09:01 PM
Hi all,

We're putting 2 1/4 downpipes, into a magnaflow resonator, into 3" pipe, back to 2 1/2 pipe in the end. We're also using dynomax ultraflow mufflers. What horsepower gain should i expect? Any info would be appreciated.

03-01-2005, 09:20 PM
if thats the only mod so far, you probably wont noptice much of a difference, i believe exhaust usually adds about 10 hp, but i never felt any of it until i put on a 5% puller for the supercharger,,, you will lose some boost with exhaust alone, add an overdrive pulley on that sc and youll feel some good stuff, that was my experiene,, buyt doing that exhaust is necessary for any other engine mods, so you're starting in a great spot, have fun with it-

03-01-2005, 09:26 PM
I'm gonna say it gives you a good 30rwhp. I got a full second in ET after putting exhaust on. Its a huge difference especially when you leave cats off. Good selection with your exhaust setup, but i'm not too much of a dynomax person.

03-01-2005, 09:27 PM
That sounds good... How much boost are ya runnin now with the 5%? I know i'll probably go down to about 9 or 8lbs... but is the 5% fairly safe? My car is a 90 and only has 70k on the clock... so its got the origional HG's.

03-01-2005, 09:34 PM
Thanks for the info guys, but i was wonderin, where should i go next beyond the 5% pully? Onto some intake, maybe a bigger top for the SC?

03-01-2005, 09:56 PM
I would consider a new MAF to replace the 55mm that you have and maybe a new throttle body. What size MAF and TB to get depends on your final performance goals.

If you want to kill two birds with one stone, I would get a 5% OD Aluminum Jackshaft pulley instead of the 5% OD blower pulley. A good bang for the buck is gears. I'm doing 3.73's in mine in May or so (stupid bills keep pushing it back)

-Andy "Melon"

03-01-2005, 10:50 PM
I was making about 18psi at 5500rpm. This is with a stock TB and maf. I have a ported blower and MP inlet plenum though. I saw 15psi with stock late model blower and plenum. My car has 153,000miles on it.