Yes. The mileage is within the margin of error for all 4 exhausts. I average 145 mpg in the summer and 130 mpg in the Winter. I just ride use my bike for regular utility transportation in my business and for personal use, so the engine is set up for low rpm torque to run between 3,000 and 6,000 rpms without lugging.Did you ride the modified SF exhaust enough to get mileage/performance comparisons with your other exhausts? I am thinking of adding supertrapp discs to a similar setup.
Also, how well does your front fender keep water under control?
Oddly enough, the modded IXIL has the most low rpm pull since I made inserts for it, and I have absolutely NO idea why. It's counterintuitive for a short exhaust to make more low rpm torque... but it definitely does. I use my driveway as a test bed, as it has a 10 degree slope for about 80 feet, and the Grom easily climbs it at only 3,000 rpms WITHOUT lugging the engine. It actually climbs easy for all the exhausts, but the IXIL works the best out of the 4.
The extra long intake actually makes most of the low rpm torque, while the exhaust helps some more.