I'm more of a function kind of guy and thinking about putting on a 4:1 system just to free up the chain side of the bike. Not really concerned that much about performance improvement as the busa is great as she is. However, I was wondering if anyone has any experience or thoughts on the M4 exhaust? I can get a full system for not too much coin. Also, can adjustments be made without buying a PC3? I would just like to put the system on, get a decent adjustment so she runs okay and leave her alone. I've heard that some adjustment is possible without the PC, but not sure.