Wanted a louder exhaust and accomplished that as they sound fantastic. Bike has an ATS set at +4, I pulled the O2 sensors and just checked the plugs. They look fine, only about 200 miles since the slip on swap. My question is, after reading numerous threads.. do I need a tuner? My intention in the first place was to avoid the cost of a tuner because I'll need both a PCV and an AT as there isn't anywhere close to get a decent tune. I was going to pick up a Lloydz IAV but it states it needs to be used in conjunction with a tuner. If I do indeed need a tuner then I'll just go back to the stock mufflers, I don't want to hurt the bike if it's running too lean.