So here is a little backround, I bought my 04 back in November and it came with a street extreme scorpion exhaust, PC3, BMC race filter and a GRE. Well one week ago today I lowsided at about sixty and messed up the left side pretty good and because I am not really using the bike as a weekend racer I wanted to take it back to stock. So what do I have to do? Will the ECU go back to stock if I take off the PC3 and GRE? The only thing that I would do is but in a K&N instead of a BMC and put the stock exhaust back on. And if I have a K&N in there do I really need a PC3? Your help and comments are appreciated.