A little KR but if your asking you sound like you want to do the right thing for your car, a 3.5 will make you happy too... Scan it on a day that has the least favorable conditions, (hot, go up hills, etc.) and thats when you should see the most KR, if its a lot then either drive accordingly or switch pulleys.

I'd invest in a MPS though if you plan on switching back to something like a 3.5 or get into heavier mods...