I have two friends that have the ISF. I have driven it plenty of times. I'm no professional drive so I cant feel the difference. The ISF feels like it pulls a little harder though. We have played on many different areas and canyon drives, the ISF doesnt keep up with me but on freeways or straights, its a coin flip. One thing I will give it is my friends have an 08 and a 09 ISF. The 08 has 60,000 miles and the 09 has about 40,000. Neither car has had any issues what so ever. Just oil changes, when my M3 has been in the shop time after time from trans to CEL, etc.....
BMC filter, OEM Exh Mod, ESS Direct Flash tune, flat black kidney grills, color painted front reflectors, LUX Angel eyes, -2012 SVT Raptor 4 dr -09 E90 M3