With the LRP28 and LRP30, I found that a more restrictive pipe does better with them than the high flow HPI pipes like the stock, ribbed or polished pipe.
I run a Losi LST2 HT pipe on mine. Helps it run more cleanly through the entire RPM range. I run that pipe with both the LRP28 and LRP30.
With the higher flow pipes, I could tune it so it would either be clean running on the low end or high end, but I couldn't find the right tune to have it run clean all the time. Back in the day, a basher I met up with ran an OFNA JP2 pipe with the 30X and it really sang with that.