Any off the shelf/as cast aluminum intake manifold that fits the FE, and flows 338 cfm average matches or exceeds most of the heads available out of the box for the FE. For years, the HR was the top tier FE, next TP, and then MR, CJ, and all the others,(SOHC excluded) Today, there are aluminum heads available with CNC programs that struggle to have an honest 338 cfm airflow at any reasonable valve lift. The KC Stage II heads only flow 338 cfm on my bench at .750" lift, and the TFS actually go turbulent and back up above ~.620" lift to 320ish cfm. A Pond, KC III, or BBM special CNC program that I have flowed still don't go much higher flow than 345-350 cfm without some tweaking. They claim 360, 370, or higher, but I have not personally had that flow on my machine. Jay Brown sent me a BT HR head that flowed 393 cfm IIRC, and that is the best FE head until his new head came along. So, yes, the "K" Sidewinder would be a very good intake for just about any healthy FE on the street. For performance, porting a RPM, Victor 427, TFS Track Heat, BT MR, can be opened up to flow 390 cfm and up. A 300 cfm head needs a 330 cfm intake manifold for the street, and a 310 cfm head needs 340 cfm intake manifold. A 340 cfm head for race needs a 410 cfm intake manifold. The TFS Track Heat is the only 4V intake that comes close out of the box to that number, and exceeds it with a simple cartridge roll of the port to match a MR gasket. Joe-JDC