I've had 1 on my 02 Viper for 10,000 miles. The Venture for 6,000. Bottom line, they work. Yes, you MUST wait for underhood temps to equalize after you stop for a break, I never punch to full throttle until I've travelled 1 or 2 miles. Consistently saw 16 mpg with the Viper and 18+ with the Venture. Both have stock exhaust. With pipes, you'l probably need a little distance before you can use full throttle. Just a guess on my part though. Good luck whatever you decide!