It adds to the intake timing, helping with really high rpm breathing.

Sweet who the hell thoght of that? So what i dont understand even more though is our stock intake timing compared to all other sorts of porting and scalloping. so can you explain these in degrees. so like how mach timing deos sp, bp, pp, scalloping add to timing over stock? And i assume scalloping isnt used with pp.

It'd be useless with a PP. I'm not sure who thought of it, but I gather that it was very secretive for a long time, and CLR was a pioneer of it.

I think it adds something like 10 degrees to the port opening time, which allows basically a bridgeport like port timing. There's some good articles about it online. www.yawpower.com has some good ones.

thanks that cleared stuff up but another question.....a little birdy told my you can only run pp on n/a cars is that true?

No, it's just mostly used on high output NA's, as it's the way to get the absolute most power out of one. They're occasionally used on some really extreme turbo cars. They're not used mostly because it's easier to add a little more boost to make up the difference.