I installed a Vmaxscart supercharger on my 1989 JDM 998. After 700 km of driving the head gaskets on either side of the decompression plate blew between pistons 3 and 4. I replaced my distributor with one supplied by Vmaxscart, replaced the head studs with ARP high-strength studs and eliminated the decompression plate. (it appeared the cylinder openings in the decompression plate were too big to properly sandwich the gaskets). I also had a valve job done and replaced the piston rings. I ran the car in for 800 km and then 300 km later, while doing a rolling-road tune-up, the head gasket blew again, between cylinders 3 and 4. Based on the condition of the spark plugs pistons 3 and 4 are running leaner than 1 and 2.
Any advice and/or similar experiences?