A 5 hp gain is almost 10%. That's not chicken feed. This bike runs WAY lean, and the driveability gained along with the HP makes it well worthwhile to go to a PC-V and Autotune. I've been running one for almost 2 years now.
The exhaust pop is caused by the PAIR valve dumping air into the header. Once the stock muffler and cat is removed, the air is no longer needed. Lift the gas tank, and you'll see the PAIR hose running down the center of the air box. Pull it off the fitting and stick something in the hose to block it off, then replace the hose. No more popping.
10 Duc Streetfighter S (black)
67 Triumph Bonneville TT Special