STIlsh has been breathed on fairly heavily to create not necessarily a very fuel efficient car but one that runs very well, but it nevertheless does fairly well on fuel considering its performance level. Full suspension upgrade with Bilstein struts all around and high rate springs that lower the car roughly 1 1/2" Whiteline bars front and rear for roll control, better brakes to replace the weeny stock rotors, 18x8 wheels with 245/40-18 Performance biased all season tires.
The engine has had no internal work done and hopefully none will be required for the life of the engine. Mods here include Cold air intake, larger top mounted intercooler, Air oil separator, Cobb catted downpipe feeding to magnaflow mufflers out the back. Did an email tune through an outfit in Massachusetts that seems to be doing pretty well. Overall fuel mileage from stock dropped about 10-15% but I got very nearly a 50% increase in power.
I guess the intake and exhaust mods qualify once I get the tuning issue tackled...see the planned mods section.
I'm looking into taking the Cobb tuning school so I can play with tweaking the engine to run slightly leaner under cruise and very light loads and perhaps get back some of the economy that was lost through the power mods.