I recently put a better flowing exhaust on my mini cooper s. I thought that this would allow the supercharger to breath better causing more power. The exhaust that I put on is a flow through muffler. and then straight piped after that. I think that the headers are what I have to change to get it to were I want it. I am looking for a little bit more power but more along the sound. I have a youtube video of the sound let me know if that is needed.

 

I guess WHAT is the problem ?
You say there is a problem ...
Not enough HP gain ?
Well what exhaust did you install ?
If it's a home brew shop built one there might not be the proper backpressure to scavenge exhaust gasses .... Do you thing the mini specific exhaust companies just build a system that fits ?no they spend tens/hundred thousands on R&D Dyno tuning ect ect

 

The problem is the raspy sound that it makes. The power gain that I got was ok. Nothing more than I expected. I read on several sites that the header is the most restrictive part of the exhaust. It is a "home brew" as you call it but in past experiences I have found those to be the best. I am going to put the header on soon and I will see were I am at then.

 

Sound is likely the muffler especially droning at speed ...
I'd try a different muffler or larger resonator ...

A properly tuned/tested system likely would eliminate this as well

 

it might be the muffler. what is the best site to order a supercharger pulley kit? Things are about to get crazy lol.

 

http://www.outmotoring.com/mini-coop...er_pulley.html

To remove the stocker you need this :
http://www.outmotoring.com/mini-coop...y_removal_tool

To reinstall belt you need this :
http://www.outmotoring.com/mini-coop...oner_tool.html

Also need a smaller belt :
http://www.outmotoring.com/mini-coop...lley-belt.html