I pulled the heads on my 1997 EFI DT150 and am getting ready to re-install them and the Clymer manual says no gasket sealer needed, the Suzuki factory manual doesn't mention gasket sealers of any kind. I've seen where others on this board have advocated the use of "perfect seal" or something named very similar to that on head gaskets. Is this a preferred way of installing outboard head gaskets and if so, where can "perfect seal" be purchased?