ok so I finally got a good street tune on my car and in the upper rpm power dies off...my setup is b20 with sc34, log mani, chipped ecu...now my A/F stay bout 12 the entire time I'm WOT...but my problem is it rips like hell until it get to bout 6 or 7 grand...I have a 2.5in DP with the same size exhaust and my exhaust has a few bends and takes a real sharp bend at the back of the car....could this be y it is dying off in upper RPM??? By the way this setup is in a EF sedan...thanks

 

Put the car on the dyno & have it properly tuned.
You probably won't be able to diagnose the issue on a simple street tune.

Also try:
1. Complete a boost leak test
2. Complete a leakdown/compression test