With an exhaust as simple as yours, it should be easy to do a baseline dyno run with the setup you have, swap the 3" on there (with gloves of course ) dyno again, then swap back to the 2.5" to make sure it comes out close to the first run, along the lines of what Helix did with the GIAC chip:

https://www.northamericanmotoring.co...t=29748&page=2

 

On a lift, it would only take 10 min to swap exhausts. The comparo would be be between my 2.5" straight, and the 3", which I'm guessing is around the box though. Not sure if that delta is something worthwhile to folks though... If so, I'd gladly entertain the idea!

 

Do you own the decibel meter or was it a borrowed item? Either way, it would be interesting to know how much of a difference 2.5" -vs- 3" makes.

 

I did indeed borrow one. I can ask Peter again, and I'm sure he won't mind.

Do we have a preliminary design yet? I'm hoping there will be a resonator a la the SuperSprint one I showed on the previous page. I would only change my current system in order to go with one that would be 3", but also straight back, and with such a resonator. If this center pipe were not to include a resonator, I could almost certainly tell you that it will be too loud, legally possibly, or just preference purposes.

Heck, I was about to hack-off my outboard exhaust hangers as I'm no longer using them. i wanted to wait 1+ years to make sure that my system was a keeper before I removed them... I'll hold-off for the time being...