Thread: Straight Pipes Off Headers

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What size straight pipe can I run off headers dump at rear axel . I'm not sure what to do with exhaust on Nova with new 355. I use to run open headers two summers with 307 until older couple next door had enough . Should of left their hearing aids out .

Originally Posted by cookster

What size straight pipe can I run off headers dump at rear axel . I'm not sure what to do with exhaust on Nova with new 355. I use to run open headers two summers with 307 until older couple next door had enough . Should of left their hearing aids out .

Run 2 1/2" straight pipe With with 2 1/2" Glasspack Mufflers with turn down at the diff . This set up will be loud but not to bad for the neighbors . Also the 2 1/2 " System is big enough for your 355 . And much cheaper then going with a 3" set up . Check out these Flowtech ones Summit # BIG-50252FLT 2 1/2 BY 18" Long .

put some good mufflers and 2 1/2" pipes all the way out the back, they tend to resonate a lot less when aimed out the rear instead of exiting under the car and pointing down. Quiet the car up a bit, but I hate driving around in a cop magnet anyway!!!! I get in plenty of trouble on the street without adding loud pipes to the problem!!!!

Dave , Those cops never around when need them or come after problem cleared. I know myself every time I do something stupid their behind me. Back to muffler theirs so many pro and cons on what to use.

Originally Posted by cookster

Dave , Those cops never around when need them or come after problem cleared. I know myself every time I do something stupid their behind me. Back to muffler theirs so many pro and cons on what to use.

We played the muffler game a number of years back with a car on the chassis dyno.... Never found more then 3 or 4 horse difference on any of them.... Unless you're going to spend a zillion bucks trying to peak out every aspect of the car and engine, I'd just buy a decent set of turbo mufflers and run them... If the basics are correct on the exhaust system, a muffler selection will never make enough difference in power that you could even notice it while driving, way too many other variables on the street.....

I was given a pair of monster flowmasters... free... put them behind my 305 in my 78 firebird. they are 3" inlet / outlet muffs, and are welded to the collector, bolted to the hedder. Used some scrap ( AKA GARBAGE ) 2" pipe to route it out the sides in front of the rear wheels. The short length of 2" seems to give me all the back pressure I need, and it sounds / performs great.

Oh, did have to weld some scuff plates to the bottom of the muffs though.

imho turbo mufflers sound better then flowmasters. i ahve the 2 chamber flowmasters they are to raspy a car with flowmasters sounds like every other car with flowmasters' loud. at least with turbo mufflers you can hear the cam alot more rather then just a rahhh raaah sound MHO

I still like dual 36" long glasspaks. Lost in the 50's.

I got a BBC with 2 1/2" pipe and the 3 chambered FlowMasters. Car has a nice rumble but sounds uncocked when I nail it. I also use a crossover pipe.