Well, on WXY's car the exhaust netted 13rwhp and 26lbs rwtq over his JWT exhaust. If I remember correctly he had a jwt exhaust. The Lebree exhaust has no bends and the difference in power can be felt in the driver seat. It will also help with spoolup and give you a little bigger power band.
Some people might not like how it looks. I would suggest that you call Greg Dupree and ask him about the exhausts he sells. He has the dyno sheets that prove the hp gains.
If you search under my name you'll find some pics of the exhaust I have.