Originally Posted by jer23
8HP is the cheapest mod ever. From gas. Just my two cents. Never said 91 was bad.
Come visit me for a good 25 hp more from your M5 after I load new software into it. And I've got one M5 I tuned with a different exhaust that had 45 hp more. (plus dyno sheets to prove it). If you use 94 octane, the software is a must-have.