So, I've been kicking the idea around lately of moving to a 4.11 if I were to buy a 9" for the GTA. While I can deal with it pretty easily because the M28 T56 I have has a 3.36:1 first gear, the gear ratio's aren't really optimal for that cam. The gear spread is decently wide, and I can easily cruise the highway in 6th gear, the car just doesn't like to run below 2000rpm, but seems to still make enough power to accelerate from 1600rpm in 6th gear. Its extremely slow ofcourse, but the car doesn't buck or do anything out of the ordinary.

But the car was built to run, and should make good power, enough that 150 abouts is possible at Road America. Sadly, I have yet to test it at those speeds since I spent most of last year just working on the tune and making sure it was running good enough before I flogged it. So I mostly drove it to/from work, and played a very short bit with it on the highway.

With the current 3.23's that means about 6500rpm in 4th gear on the driveshaft.

If I were to use 4.11's then that would put me in 5th gear around the same MPH, and driveshaft speed would actually be closer to 8100rpm.

The M28 gear set for the T56 trans has a .80:1 5th gear.

That speed concerns me. I have a DS Loop, but would rather never need to actually put it to the test.

I'm guessing that were I to go with 4.11's, I'd probably have to move to an upgraded driveshaft.

 

There are people who grew up with 4 speeds and feel 26" tires and 4.56 gears are ideal. So the engine is constantly in "go" range.

I'm the opposite. I like overdrive and the feel of an engine pulling properly from 1600 without downshifting all the time.

Take your "Feels good" out of the equation and figure out if you're actually going to run harder or faster by going with your proposed changes. I'm guessing @ RA, you're running in an RPM range that makes the 1600 on the highway irrelevant, since you're not going to be running in 6th at that track.

You could fine tune 5th and 6th with a TR6060 custom build. But if you're just looking for small changes, a 3.42, 3.55, 3.73, or 3.90 rear gear are all options for the 10 bolt before you go 4.11.

Your current 3-4 rpm drop is 26% and your 4-5 is 20%.
There aren't huge changes to be had by stock gearing in those shifts.

But going to separate 5-6 gears in a TR6060 can tighten up 4-5 and 5-6 significantly. I can tighten those up to about 15% each in a T56, but that's a custom build.

If you haven't run RA yet, maybe a year 1 run with M28/3.23 and some time with a spreadsheet to see what you really want to do with the car, gearing-wise is in order. More driveshaft rpm isn't a good idea. If all else is equal, reaching your top end in 4th is better than reaching it in 5th. Not only due driveline rpm, but also, transmission direct drive of maindrive to mainshaft.