No Dyno numbers, but this is what a well used, broken in Invidia system sounds like:

 

Mmmmmm. Tasty.

Also, for the OP, check out the exhaust sticky: https://www.northamericanmotoring.co...clips-etc.html

 

I made one out of 2.5" straight tubing and a large resonator (glorified glass pack), it's loud and pops and crackles like crazy, but since it's straight back it actually makes good power. I have two slight bends in it, one as soon as it exits the main tunnel under the floor to slightly bend up, and one slight bend right after the battery box to keep the dual tips up a bit. It sits against the bottom of the battery box, but I've had it like this for almost 3 years now with no issues. It does have a bit of droning on the highway like most this loud do, but it's the price you pay. I'd say it's probably a bit louder than the Invidia clip with a much more pronounced "blurble" and a slightly deeper tone.

All in all it cost me less than $250 to make including a new mounting design, but not including a few hours of fabrication time and mig wire to weld it.

 

The exhaust systems all sound the same for the most part:

 

I have a M2 performance exhaust on my car I think I paid somewhere in the ballpark of $450 for the full catback exhaust and it sounds great I get compliments on it all the time.I've had it for about the past 3 years.

Here is the video I made.

 

Good point. All engines have a particular sound and the exhaust can only manipulate that sound so much. That's why you can't bolt an exhaust on to a MINI and make it sound like a thundering V8.

Here is a good video (although long) on exhausts. It shows how much is involved in designing an exhaust. Once understood you may select your exhaust differently. Just throwing pipes together to make your own exhaust is kind of a crap shoot at best, although it certainly can save you money.

https://www.youtube.com/watch?v=