I think they were common on 380bhp cars. I went for 1000cc as a future proof which was a good idea as my new engine is likely to be way more.

I think you should add a WRC style metal gasket to be safe too.

A good intercooler is a wise precaution and ideally a large bore down pipe and exhaust as they can be restrictive at 400bhp.

The expense comes in when you do away with the laggy old T35 / 38 turbos and go for something modern.