Nice car man, I love the hard top. He said he put down 210whp at 10psi with that intercooler... that is very realistic. Even if it was 240whp at 10+ psi, that would be realistic as well if it was done with that intercooler. When you are running that low amount of psi, that size intercooler that is on his Miata is all that is needed. MANY people overkill when it comes to intercooler size and the amount of psi they are running. The end result is that you end up hurting your performance when you run one that is too large. Here is an example -

A 1G DSM stock side-mount intercooler is good to 300whp. Many people have proven this. I guarantee that FMIC on his Miata is larger than a 1G DSM side-mount intercooler and that it works perfectly for his set-up. I would much rather have an intercooler that makes my engine perform strong and efficient for my set-up, rather than my car 'look cool' because I have a big FMIC to show. PSI is an arbitrary number, and having the right size intercooler is important when matching the size of it to how much air, or psi, you are pushing through your engine.

You have a really nice Miata man, I bet it is really fun to drive, being boosted!