The best head gaskets for a Subaru WRX or STI engine build are multi-layer steel (MLS) gaskets from Cometic, sized to your bore and offered in several thicknesses so you can fine-tune compression. Cometic MLS gaskets seal reliably under boost where stock-style gaskets can fail, which is why they are the go-to choice for turbocharged EJ and FA engine builds.
Cometic is one of the best-known names in performance sealing. An MLS head gasket is built from several embossed stainless steel layers that conform to minor surface imperfections and maintain a seal through heat cycles and cylinder pressure. When shopping, match the gasket bore to your piston bore, pick a thickness that gives you the compression ratio you want (thicker lowers it), and plan on fresh head bolts or studs any time the heads come off.
This collection covers Cometic head gaskets and full Street Pro gasket kits for the Subaru WRX/STI (EJ20 and EJ25), Mazda Miata BP 1.8L, Mazdaspeed3, and Subaru Legacy Sport, among others. Pair a gasket refresh with ARP Fasteners & Hardware head studs for even clamping load, and while the engine is apart, check ACL Race Series Bearings, King Engine Bearings, and Wiseco pistons to complete a rebuild. For background on the engine these gaskets serve, read our guide: Subaru EJ257 Engine: Everything You Need To Know.
Popular picks include the Cometic 100mm bore head gasket for WRX/STI EJ25 models and the Cometic head gasket set for the Mazda Miata 1.8L BP.
Cometic Gasket FAQ
What is an MLS head gasket?
Multi-layer steel: several embossed stainless steel layers that seal under high cylinder pressure and heat. It is the standard upgrade for turbocharged and high-compression builds.
Do I need a new head gasket when rebuilding my engine?
Yes. Head gaskets are single-use — always install new ones any time the cylinder heads come off, even if the old gaskets look fine.
How do I choose the right bore size?
Match the gasket bore to your piston bore. If you are unsure, check your engine's specs and your year and model before ordering.
Should I run head studs with a Cometic gasket?
For boosted builds it is strongly recommended — quality studs provide more even, repeatable clamping than stock bolts. Keep torque specs and sequence from the manufacturer.
Cometic
