will fenders off a 2011 fit my 06 without a problem? bumper too? both 8th gen so id assume. but mines an si and the other one isnt. and the other one is alot newer

 

yes

 

If it's coupe to coupe or sedan to sedan, the fenders are the same on 06-11. As for the bumper, assuming you're talking about the front, you'll need the upper grill for the year of the bumper (06-08 and 09-11 front bumpers and grills are different from each other). And again, sedan parts are different from coupe.