Doesn't work for me. I prefer the more understated factory versions. As for the seats I will say this. I have been in two ST2s and if you are a bit broad of beam the Recaros could give you some trouble. Having said that I fit fine and would find myself longing for them. The headrests in the Shelby look to be more accommodating of helmets though. As for mileage I have gotten 30 mpg from my SVT on the highway with the AC on at 75-80 mph. I don't see 40 in the realm of possibility. What kind of suspension upgrades? Looks lowered so the already firm setup is even firmer with less travel. Not what I need for the roads in my area. The Borla is not as sexy as the stock setup. This looks like a track toy more than a daily driver. If you really want to improve on the original increase the size of the gas tank by three gallons and loose the full size spare to make a bigger trunk. My SVT has more gas and a bigger trunk by far and I have the subwoofer eating up a few feet. Stll want one though.