I put a d&d fat cat on this past weekend and upon completion the bike wouldn't fire. Fuel pump wasn't priming so started checking fuses to see if I grounded the O2 wires somehow and popped something. Found the ECM fuse blown. Replaced it and hit run switch and t blew again. Called my friend at the Harley service dept and he said don't worry probably a fluke accident and a wire is grounding somewhere. Had a truck come pick it up for me and bring it in only to find the ECM completely fried. New ECM ordered under warranty. Had him check the exhaust flanges since I couldn't crank for leaks and he said I used the wrong nuts when re installing the exhaust. Have no idea where I got the wrong nuts since I only had the ones from removing the factory pipes. He told me don't worry he will remove the head bolt and replace and all will be good. Then I get a phone call that the head bolt is stripped into the head and they will be ordering me a new head! Luckily they are covering all the parts and most of the labor under warranty. Who would've known a simple exhaust kit would cause this much problems... Sheesh...