IMO...equal drivers, Mach 1 all day...Good driver in an 06 vs bad driver in Mach 1, edge to the 06...CAI is ruled out because you both have them, however the Mach 1 has that killer ram air scoop which is 10 times better anyway. The exhaust doesn't mean too much because it might just be an axle back. Even if it's a full exhaust the 06 is still heavier. The Mach 1 also has more power from the gate. All in all I'd put my money on the Mach. Just make sure to look under his hood for a hidden nitrous system, underdrive pulleys, etc...he might sneak a tune in but that should just about even things up...