- Apr 10, 2002
I just purchased an XCal 2 for my 2002 GT. I only have a drop-in K&N, an off road MAC prochamber midpipe, and a Bassani catback. I ordered the gear kit from americanmuscle.com with the 4.10 gearset, so I know what to expect from that. But what kind of gain should I expect to see with a 91 octane tune? a 93 octane tune?