I have a LS block that is RS MACHINES Sleeved. IE its a 84.5mm Bore with a n89mm crank(LS). its slightly larger than a 2.0.

To answer everyones questions, the debate has been raging for years abot which one is better.

To SK8PHAZE, have you ever seen an ITR head, the P&P is MINOR AT BEST. why did they choose a B16 casting for the ITR< mainly because the ITR has the highest compression out of all B series, and that a gsr head would have raised it another .3. THe differences between a B16 3rd gen head and a ITR head (port wise) is about 20 min of mild portmatching. And thats TOTALLY WRONG INFO about flow characteristics. SHOW ME PROOF, show me Flow benches of CFMs per head. what you dont realize is a ported head (a quality job) will make the heads damn near identical. we are talking about stock vs stock.

GSR head is a BETTER street head, what you guys dont realize is that secondaries and the GSR manifold =MORE TQ on the street and in the midrange. Which is where your car will be fast. GSR head is a better street head IMO. B16 heads are shitty, but id personally run a GSR head if i could. the quench pads of the GSR head also push the flamefront in the combustion chamber together for a better burn than an open B16 head