They are claiming they put taper in the liner, which would be a big improvement over the engines I bought with made in China on the case. All 6 of my engines were the worst engines I ever owned and transplanting the piston and liners with the Brian Gardner sets was a complete 180, making them into great engines.

For stunt flying I've had fairly good luck with piston fits on the blue ones. My experience is the rest of the engine will out last the ABN system and I do have liners with brass showing. This allows for rebuilds so, if you buy the new version, my advise is buy an extra P/L and wrist pin (pads wear out) and you'll get double the life out of it.

Motorman

Don't worry about the brass showing.  It doesn't affect anything if you have a good piston seal.  My first LA wore out one piston and liner breaking in the shaft.  The next season I bought a new P/L.  It had brass showing in exactly the same spot but broke in just fine and ran at least 2 years more 200 flights.  When that setup went south I looked through my parts box and found a used piston and liner, out of 4 sets, that had a decent amount of pinch.  I put all the parts into a new silver case(the old blue case had a broken intake).  The new case was slightly undersize so it took a moderate amount of pushing to seat the liner.  The fit tightened up a bit when it went into the  case.  After 5-10 breakin flights it is running great.