i 1st got a BDS st2 and did not like what it put out so i got a blowershop w/teflon and put the BDS on the shelf.the rotor to rotor, to case clearence on the BDS is .020.i even sent the BDS back to get run tested and got it back without the snout coupler,eventualy thay sent me a used one to replace the new i had on there.learning this blower stuff gas been interesting.