Heat rejection and pressure drop are what determines the core effectiveness but not necessarily the best intercooler for an application. Its impossible to have zero pressure drop if the air is actually being cooled. Having the most heat rejection and the least amount of pressure drop physics will allow is a good determining factor. Larger cores are heavier, block a lot of frontal area impairing the cooling system and are adding weight to the nose of the car and may not be any more effective than a smaller core or a stock location core. Ive seen large front mounts perform poorly and small ones like the old discontinued Precision front mount work well into the 9's. The engines air flow can be determined by the speed and displacement. A 231ci engine only flows about 370cfm at 5500 rpm and at 6000 rpm its only about 400cfm. So not a lot of air flow. The open cross sectional of the tubes in the core could be calculated and an approximate airflow calculation achieved. Looks like a core that flow about 400-425 cfm and has good heat rejection will work well down into the mid 9's. You would not want to run an intercooler that flows less air than your engine will use or it will cause a huge pressure drop as the engine airflow increases beyond the intercoolers airflow capability. Its possible to have excellent heat rejection and poor flow also. What you would see is high pre intercooler pressure/temp and considerably lower manifold pressure but the charge air will still be less than 15% over ambient. Seems like its doing its job but its not. This also has a very negative effect on the turbos ability to turn the air into kinetic energy because it will stack in the diffuser. So youre having a huge pressure drop and your turbo is heating the air more than it otherwise would compounding the problem. There were a few different intercoolers out there that did just that even though they were sold as the biggest and baddest out there. One of them was heavy too. Really heavy. The piping doenst matter too much since the cross sectional area of it is more than the tubing in the core. Having a slow tapered transition when going from small to big at the compressor housing outlet is very important for the turbo to perform at it full potential. Any rapid change in inside diameter can disrupt the turbos flow potential. So the best thing is to have an intercooler with very good heat rejection, minimal pressure drop, be as light as possible, and mounted as far back as possible to gain an advantage. having a 30lb heavier than needed intercooler wont hurt power but will make your suspension work a lot harder especially on the street. Poor weight transfer equals piss poor traction. There is very little useful analysis out there on the different intercoolers. Without showing why one is performing poorly or one is performing well with actual data no useful conclusion can be drawn.
