For lowering lap times in HPDE, resist the urge to add HP to accomplish that goal. Focus your engine mods on extending the life of the original engine as long as possible, ie proper oil cooler, baffled oil pan, catch cans, etc. From experience, I would add E85 to that list of simple mods that provide “insurance” to the stock engine, especially for the Gen 3 cars since it’s such a simple conversion. Lap times are going to benefit more from good tires, proper track alignment and seat-time.
I agree with that as well, but I would add good brakes to the list. FWIW in my HPDE experience cars that are slow or don't handle all that well can still be heaps of fun, but cars that don't stop consistently erode your confidence and that kills the fun very quickly.