It depends somewhat on what muffler you choose. If you use a muffler with the inlet centered in the muffler you will probably want a 50mm drop, but honestly it's been like 5 years since I dealt with these planes so it's not easy to remember.

BTW for anybody else who still has one of these I have a new fuselage for a red one, just the fuse, no hatch or canopy or anything else. $300 shipped.

TF