I have a full system only with Silmotor hearders and I had the stock ECU re-mapped at BCM in Laconia by Kyle and the bike runs perfect with or without the insert with no lean back-fire. The driveability is excellent, smooth even at low RPM. I have never been happier with this bike.

For anyone who has sporting tendencies, the Multi makes a great touring bike, my only recommendation would be a Corbin seat.
I have done 300 mile days and was ready for more, the Corbin seat really gives great support. I have the big hard bags and made the mounting hardware easy to get on and off to ...