Can you guys refer me to a tuning shop in So Cal? I suspect the exhaust system in my car is robbing me of performance. I want to verify this before I go replacing the system. The previous owner installed a single 2 1/5 inch pipe from the front to the back with a japanese ricer type exhaust. The hole in the exhaust pipe is a measly 2" in diameter if that. I still have the stock exhaust. You guys think I should install that instead? Car is an e30 m3.