Cosworth do a load too
87mm is fine. Has been fine on mine for almost 2 years.
Cometic have horrendous reviews.
Never been on a rolling road but at 12psi it's probably around 300. I have seen people with big power GTi-R's using them with no issues. It is supposed to be one of the best gaskets to get.
I'm not criticising because this looks like an awesome build but that's way too much power for a FWD Micra. Try running a basic boosted DE first, I bet it would be more than enough!
87mm is fine. Has been fine on mine for almost 2 years.
I might just go for that then, and when you say more than enough what do you mean for? I can build this the way i plan and map it for the horsepower goal then fine tune everything so that it can put the power to the road etc. i really dont wanna do it all twice unless it breaks