I have an M4 slip-on. It feels like I've lost power (torque?) off the line - after the exhaust swap. Should i get the dynojet jet kit and K&N filter?

True richen up the air/fuel mixture. Turn them out half a turn per test run and see where it's going (worse or better).

For sure a jet-kit will help a lot to get back torgue ... actually it will ad more power through out the whole register.

Just ordered the Jet Kit from IVAN. I'm very optimistic on this kit since I've heard alot of good things about him all over the net.

You will be very happy with IVAN's kit for the R1, I think he has the best kit out for this bike, and a few others. let us know what you think once you get it installed.