[RKDinOKC]

The Autothority Chips and Banjo Jet have a reputation of over-boosting and blowing head gaskets. That is why with my Turbo S I went with Weltmeister Chips with waste gate shim. Made 270 rwhp and no problems, bulletproof for 3 years. If you already have wide fire and o-ring the next thing to go is the girdle will stretch (crank and rod bearings), and bent wrist pins from pre-detonation. I learned with the second 951 I bought. It had an autothority MAF and chips with wide fire and orings. 10K on a fresh rebuild and luckily my mechanic heard rod knock before it cratered. With the K27-8 Turbo it was the absolute quickest, but it didn't last long.

The banjo bolt restricts the available air signal to operate the waste gate. The Shim just increases the pressure about 2psi to open the waste gate. You really don't need to increase the boost much because at 16psi of boost the stock valve springs let the intake open on the exhaust stroke and you get valve float which means lower hp returns for higher risk of engine failure. There is a point where more power from boost just means more wheel spin and the car is much harder to drive. It either has too little or too much as the turbo kicks in.

Spend the monies on suspension. With just the Welt chips/shim, suspension, and street tires I was able to keep up with 996 Turbos with good drivers on race slicks at the local track and it was the car to beat at local autocross. My problem then was keeping the brakes cool.