take the picture and measure the fin area, I did this in MS Paint by noting the pixel coordinate for the left, right, top and bottom, the stock IC's are 167 pix wide, same as the fin width of the IPP IC's. That's measuring to the edge of the fins, if you add that thick solid area on each side of the IPP IC's they're then larger than the stockers. Stock IC's are taller. The IPP's are thicker than the stock IC's which makes a big difference in the core volume.

Of course those numbers could be off because of the way the picture was taken. It also doesn't say anything to endtank design and the internal properties of the IC's.

National Motorists Association