Im thinking about gettin rid of my ractive muffler and just running straight pipe. I have 2 1/2 in. piping all the way down with no cat, what kind of HP increase would i expect from this with no muffler? Are there any drawbacks to running straight pipe? I have an 83' 280 ZXT by the way.

 

What kind of power increase over having a muffler?

Usually not much, but a turbo might be different. I'd guess anywhere from 3hp to 6hp just with the loss of backpressure. If you go from the factory exhaust setup to your straight 2.5 inch pipe now that would be a bit bigger change in power. Not sure how much though. Depends on your boost level and other factors of the engine. Still, only 10-15hp max increase...

but it sure will be loud!

 

any gains for an N/A?
my pipes and muffler are all rusted out and i was thinking of running straight 2 1/4 pipes.

 

No muffler on a straight piped ZXT is loud. I had to drive like that once when I was swapping turbos out to get to a local craft shop. Way too much resonance inside the cabin and good lord, you can't hold a conversation or listen to your music without cranking the volume or shouting. I dunno if you gain hp with no muffler, I think the Ractive mufflers were a straight through design type so you wouldn't gain much since they are pretty free flowing. You might gain a few hp's.
As for n/a, I can't tell ya how much you'll gain, but when I went to a dyno shop, some guy unbolted his Sentra Spec V and did nothing else, and his car dynoed out 5 hp and 7 lb/ft of torque more than his first run, but dude was his car an ear drum blaster!
John 82ZXT

 

N/A gains are less as they have less exhaust flow. 4-7hp is a typical increase for an exhaust system. Running a straight pipe on a larger exhaust vs. the same pipe with a good muffler is probably only 1-3hp difference. Very minor, and only at peak rpm does it matter that much. don't do it!

 

ya i guess ill leave the muffler on...I might buy a different one though

 

right.
thanks.
guess dynomax then?

 

I've heard good things about Dynomax.
I heard a 240Z (2.8L dual SU) running a 2.5 with a glasspack and dynomax straight through muffler at the end. It was very quiet inside and outside had a nice mellow hum.

I see they make those with fiberglass inside for sound deadening. I wonder how long those mufflers last... anyone know? Probably longer than the glasspack...