I installed the Magnaflow SISO catback on the truck this past Saturday. Much improved sound. It's still nearly silent when cruising, but sounds great when you get on the gas. Well, I kinda wondered about any performance gains, and was pretty sure they'd be minimal. So I decided to make a few runs this morning with the Gtech and see if it noted any changes. Here's the numbers:

Before:

0-60 in 9.4 sec
1/4 in 17.14 @ 81.7mph
60ft in 2.65 sec
330ft in 7.29 sec
HP 176 @ 4829 RPM
TQ 226 @ 3377 RPM

After:

0-60 in 9.2 sec
1/4 in 16.94 @ 83.2mph
60ft in 2.57 sec
330ft in 7.15 sec
HP 199 @ 4789 RPM
TQ 238 @ 3886 RPM

All numbers are the average of 3 runs on the same road, in the same conditions.

 

try it again in a few weeks after it breaks in some more. You should also notice a slight change in sound (deeper and louder) too. At least I did with my SIDO side exit catback.

 

Yeah, then after it gets louder, it seems to get quiter because you become accustomed to it IMO. I love the sound of mine, I have a SISO too.

 

Those gains are impressive!
Much more than I would expect!