I took the rubber collar off and I didnt notice any difference. The engine didnt seem any hotter or cooler and no noticable gains in power. Might as well leave it alone and save money for an intake.
I agree, if your not going to notice any gains then why bother taking it off ?? it's like you said..wait until you get a cold air intake and do it right the first time..
If your referring to the Hydrocarbon Trap ?? you need to read over posts 2-4 again..The 05+ has never had an air silencer in the stock airbox..Your thinking of the air silencer that was used in the old 94-04 cars..The only other device found in some 05+ mustangs are called intake pulsation tanks that are attached to the bottom side of the stock rubber intake tube..And again, only some 05's and up have them and were installed only on cars with automatic transmissions..