Originally Posted by 2001TEGGSR

From an OEM standpoint, the ITR version of the PR3 will outflow the p72. The OP already has a GSR head though, which he can get ported and polished for significantly less than the cost of a then inferior ITR head. Not to mention, he will suffer a slight compression loss with the ITR head.

In almost all cases, it doesn't make sense to pay top dollar for an ITR head.

Take one of each, PR3 and a P72 - do the same port & polish job, and the P72 will always flow a higher CFM. Its been proven on a flow bench several times.

Now just to add, if I were doing an LS vtec setup, I would buy whichever I could find cheapest - the GSR p72, or the B16 pr3.