Hey Dougie. Sniffin about the scoobs again are we?!
Me being pedantic here, but it's Sam Ellasar, not Ellis.
Standard internal's could well last at 1.6 BAR, but in my own personnal experiences, it won't for very long, unless your fairly lucky. I can't remember how much boost Alan was running, or even Scoty, or anyone else, but by fitting headers, you lower the boost for the same power, which is in my eye's, quite a safety precaution.
I'm sure Sam could well map the car for that boost if you wanted to, but i doubt he would warrant the map work, for running that amount of boost.
Rambling on a bit now, so i'll leave it at that now.