Well, just took of my cat back E36 M3 exhaust bec my tri-flo is waiting to be bolted on and wow..............Start the car up and it burbles like no other, rev it under 2 grand and its kinda like a deep grow... romp on it and that BMW opens up like I have never heard in my life. Honestly its the best sounding car I have ever heard until I put the tri-flo system on. W/ the tri-flo its much smoother, not rattling and bubbles and whales more. Also I noticed a significant power/torque increase. Anybody here running cat-back/baypass valves (no cat-back) ? I would highly recommend baypass valves with a switch if you really want a sick car.