Before i posted this thread I did use the 'search' function but couldnt get any help from those.
I have a 1997 Z28 all stock, I want to go with a flowmaster muffler vs the whole catback system. I looked on carid and the 80 series comes in a 2.5" in/out or 3"in & 2.5"out, soo which one works for our cars?
And is the 80series muffler the loudest? Or the 10 series or 40 series loudest?

 

The limitation in the exhaust is the 2-3/4" crimp bent intermediate pipe. That's why a 3" mandrel-bent system actually improves performance. If your primary interest is "loud", put a cut-out on it.

If you seriously want the Flowmaster, get a 3" in. And the stock muffler is a dual outlet cross-flow, so it needs two outlet pipes, one on each side, 2-1/2". With Flowmaster, the lower the series #, the less flow restriction and the louder the sound.

 

U TUBE has a lot of sound clips there.

 

Yea fatdog2, i have listened to alot of clips on youtube. Right now just want something louder than stock. The flowmaster mufflers are cheap and get the job done. Injuneer answered what i was confused about. So its 3" in and 2.5"out. I believe i gotta go with 80series eith the dual outlet.

 

Let me measure my stock muffler. It's still in the attic over my garage. Now I can't remember if the stock intermediate pipe necked down to 2-1/2" or expanded up to 3". I would still consider the 3" in, in the event you decide to go to a 3" intermediate pipe in the future.

I had a 4" Mufflex catback with a 4" in/single 4" out Flowmaster race-series (10) muffler. The single outlet had a tailpipe that turned down just in front of the bumper. Basically, there were no exhaust components/tip visible from the rear of the car. Actually didn't look too bad... sort of stealthy.