Need to upgrade exhaust for street/strip. Any suggestions?

[mikew88gt]

Hey guys,
I wanted to get some input on a whole new exhaust upgrade. My current system consists of MAC 1 5/8" equal length shorty headers, MAC 2 1/2 "H-pipe and Flowmaster Force II. This was OK when the car was a basically stock street car. Now I'm looking at a 347 stroker with my existing heads, intake etc. The car is used mainly for 1/8 mile drags. I drive to the track but I'm willing to live with a loud exhaust. I've talked to other guys at the track and get mixed results. Some say my shorty headers are killing my power. Most guys almost laugh when they hear that I'm running 3 chamber flowmasters on the current combo. I'm leaning towards the BBK 1 3/4" full length headers but the rest of the exhaust is in question. Will a 2 1/2 " exhaust be enough for a 11.0 to 1 compression 347 and nitrous?
Let me know what you think. Thanks.

[Dark_5.0]

You would be surprised how much HP 2 1/2 inch exhaust will support.

Starting from scratch i would put some 1 3/4 long tubes on there with 3 inch exhaust. But considering you already have the equal length headers and 2 1/2 exhaust you might consider some cut-outs for the track as a cheap option.

I'd keep the 2.5" exhaust. With the power that the 347 will be making, I'm sure you won't always be juicin it...so I don't think the 3" exhaust will be necessary. Last year I got rid of my 2 chamber Flowmasters that I had forever. There are MANY other aftermarket mufflers available today that are produce more power and are quiet. Last year I put a Dynomax Super Turbo cat back system on. It definitely boosted my power. I could feel it the first time I drove it even! My 1/4 mile times dropped over a tenth from this one upgrade. Plus it's much more quiet. But once you bring the rpms up or nail the throttle it roars pretty good. I definitely like the sound of my exhaust better now with the Dynomax. It sounds much more crisp & healthy. If you plan on changing the headers, I'd definitely go with long tubes. Not sure what size on the headers though. I haven't ran long tubes for probably 10 years, since I sold my '84 GT.

[mikew88gt]

Thanks for the replies. One of the guys that thinks my exhaust is holding me back runs the Dynomax on his car. He can drive around town (if he's easy on the gas) and most people hardly look twice but if he nails it the car is all race car. That's kind of where I want to be. Mainly I don't want to give anything up at the track and if I have to baby it around town I'll do it. So far this year I think I have less than 200 miles on the car so I'll take my chances with the local "Reno 911". The reason for my entire upgrade is this. If I go with full length headers then the H-pipe won't fit anyhow. The 3-chambers are gone anyhow so that's why I'm starting from scratch. I just don't want to buy an entire exhaust that will be a small step up from where I am now if it's going to be costing me with my new combo. I appreciate the input.

[ols0051]

I just got done cutting a small spot out in my firewall/floor area because my 1 3/4 mac long tubes fit like shit. The problem could be the height of the energy mounts, but anyway, with 3'' collectors, custom make a H-pipe with the crossover tube just behind the crossmember, 3'' in/out dynomax bullets dumped about a foot short of the axle. ='s one nasty sounding stang....

[mikew88gt]

I like the way you think. Maybe I'll spend my money on a good set of headers and fabricate the rest of the exhaust around a pair of dynomax mufflers. If I can get it done in the next couple of weeks I'll let you know what kind of difference it made on my current 302. The 347 is my winter project.

[ols0051]

You will like it. I have just a carbed 302,heads etc.etc..The H-pipe we were able to easily fit together with no major issues. we kept the pipes along the edge of the driveshaft tunnel. "wanted to not see it from a side view". got the muffs from summit $35 a pair after rebate, and $200 for labor at the local shop for bending, welding. PM sent...