Thanks for all the input guys... I havent heard of anyone using 2617 pipe... What would be the differences between the 2617 pipe and the 2607 pipe? Also... Has anyone found the differences in top,middle,bottom on the JP 2620 and the 2602 pipe? The diameter at the ring changes so I guess something must change. Seems that everyone or most have stopped using the all famous Skyline VR12 plus pipe in their engines.