If your paying cash, then you have a few options (no doubt Joe pm'd you) however if your happy to let MMS sort it all out, then they will (well at least should!!) look after ecu / engine / any problems that will arise.

You could do a full rebuild with strengthed internals et al, however the EJ207 comes with better guts already so really, this is probably the easiest option when itcomes to strength, power and reliability VS cost!