Hi all, I'm way out of the loop for all this, so any advice would be appreciated. Tried the search, but lots of info kinda spread around, its hard to gather.

I have a 99 Z28, pretty much stock engine and exhaust wise, except for a SLP loudmouth (with a "bullet muffler" mod)

Well, my DEQ here now enforces sound checks(yay to technological progression ).. Its something like a 93 db limit at 2500 rpm, mics are like 1 or 2 feet away from each exhaust outlet. And I failed.. I think i got about 98 db or something.

I'm looking at the Flowmaster American Thunder 17199 exhaust.. price seems relatively cheap.. I notice its not stainless steel.. From what I gather, this exhaust is relatively quiet? Thats what I'm looking for now.. (getting old i guess too heh)

Is this a good pick for my needs? Or do you guys recommend something else?

 

Do you have a catylitic converter on your car? It not, put one on for the test; this will temporarily quiet it down (assuming you want to keep the loudmouth exhaust).

The flowmaster exhaust isn't too loud either. I have the single out rear and can barely hear it unless I am getting on it.

 

look into hooker exhaust to quiet it down. also, yes, do you have a catalytic converter? You could also put in some of the cone inserts to quiet it down a little bit. Flowmaster is one of the worst exhausts you can put on these cars.

 

I got cats, and even with them, its still plety loud.. 98 db at 2500 rpm. Technically, this car won't be able to run at some tracks with sound limits, although I was never called on it to do a soundcheck at the tracks.


Yea, I remmeber hearing a long time ago Flowmasters are bad for performance in the past, but I don't really remember anyone actually proving it on a stock car, and comparing it others? Nobody can confirm how that "saying" got started. Even so, it can't be worse than stock.


Besides, any catback with a muffler will be less freeflowing than my current SLP loudmouth. A part of me is going to miss that sound.

Cone inserts huh? Think they can reduce it by about 10 db though temporarily? I'd imagine they have to be some really tiny holed cone inserts to do that!

 

Get a magnaflow catback...they are all stainless, they actually flow (compared to flowmaster) and they aren't all that much...should be cheaper than the SLP.

Get the car tested when the exhaust is fairly new, as they get louder over time.

 

yeah, idk how far a cone insert will reduce it.

as far as the flowmaster, theres been dyno tests that have proven 10-40hp on fbodys depending on mods

 

I personally love my flowmaster catback. Sound is deep and plenty loud for me. I switched from a SLP loudmouth to flowmaster. I liked the sound of the LM but when cold it is to raspy (to much popping especially when decelerating).

I personally believe that flowmaster exhausts flow as well as any other catback out there.