I have a tuned .28 and a modded .21. I only sealed both sides of the pinch bold on both engines and they have been perfect so far. i don't have much runtime on them yet. I'll start sealing the carb next time I take them apart, just to be sure.

I just got a 2053 pipe to try on the tuned .28. From what I hear, the pipe holds the engine back a bit, but in exchange you get very good runtime. I first tried a MSR 1005 w/6mm restrictor and was not to impressed. It did run good, but not the power I expected from a 28. The engine was still very tight and should get better as it loosens up. My Powerhouse modded .21 has a JP-1 pipe (recommended) on it. With a 6mm restrictor and the engine is still very tight, preformance was just good. I changed to a 7mm restrictor and have not yet ran it again.

I still have a couple of pipes to try.
2050
2060
might buy an 053