We do use the Indy block a lot and they workout just fine, We would never use a aluminum world block. The thickness between the sleeves would be all the same between the blocks based on bore spacing. The only difference would be sleeve thickness and we use the thicker sleeve option on most high HP builds. The thick sleeve on the Indy leaves .160 between the sleeves and the std sleeve has .320. Not tin foil by the miss informed tech guy. If anyone compared the two blocks in person and used them to build engines and inspected them after running them you would pick the Indy block hands down. Our highest HP engines have been with Indy blocks, the new KB may change that though, but that's a different story.