speaking of the Gen 4, that body design has for lack of a better term "cab forward" that is to say about half of the engine is under the windshield making engine assess tight in the original package.
The body is a good aero package and because of the front to rear weight balance they work well as drag racers.
The cowl/windshield/wiper area sheet metal can be easily modified to greatly improve engine assess but doing so is not legal for a stocker or super stocker.
This build up link has some information about modifying the cowl.
http://classracer.com/classforum/showthread.php?t=60348