yes. If not a huge diff on the dyno, there will be a definate sotp difference, and the sound makes you think your going faster also. What exhaust do you have now, and what are you stepping up to?
The car will feel a lot stronger but you're not going to see nearly the difference that you would if you installed headers. You ought to wait for the headers and then do the whole install at once.
Hopefully I can get the FRPPs for under $50. The boy I'll get them from is the one I'm getting the Hpipe from. It's a Mac 2.5". $20 is what I'm giving him for it. I plan on doing long-tubes, but that'll be next spring probably.
You probably will feel a little SOTP difference. When you remove the mufflers you lose backpressure which makes it feel like you lost torque (whether you actually do lose it or not I'm not sure.)
My '88 has equal length headers, stock h pipe and no mufflers.. and it feels like it has no torque. I can't even squeal the tires from a dead stop. I bet if I swap some flows on, it would feel much better. Let us know how it turns out.