I think of getting performance out of a 4Banger, old or new, I think engine modifications (or, thanks to the guys here, Gearing). If we were talking a different vehicle, then maybe I'd think shedding weight, too, so the engine doesn't have to pull as much.
Recently there has been some talk here about automated manuals, paddle-shift etc and that probably caused me to remeber that I hadn't changed out the gear oil on my 4Banger's 5speed and transfer case in about 50,000 miles. I did that the other day and I also did the differentials, too. I ended up using a Royal Purple Synthetic Gear Oil all around, about 10 quarts of the stuff!
After doing the gear oil change, I noticed that I was able to change gears about half-again as fast as before (Obviously no supercharger-type power improvements to the rear wheels, etc; just faster gear changes).
With the faster shifts, it seems your RPMs don't have as much time to drop as you upshift. Thus your engine is in a slightly "meatier" position as you are able to advance more rapidly through the gears. Changing to a good synth tranny fluid is not real expensive and it may help you use your engine a little better.
