$3500 Down the road from me

[spareparts]

Ferm, I haven't seen any OMC loopers with that much compression, I know on the mercs we mill the heads to get 140 psi, anything above 145 we start running race gas or octane booster, on the 3.0l mercs, 135 is about max before the expensive gas, most of the OMC loopers I mess with show around 120, could just be my gauge or it could be the thick head gaskets