I have an '86 i'm putting back together, it has stock head pipes and the 2 kerker slip ons. The previous owner says he bought it from the original owner who stated they put a stage 4 kit and pipes on it at the dealership. What would this stage 4 kit consist of and is there any identifying components to verify this is what is installed? Previous owner says it has great mid and high but low end has sufffered. I'm just wondering if they just threw a set of slip ons at it and left the stock jets in. The bike sounds good, just wanted to make sure i don't have to rip it apart again after i put it together. :confused2: