I was told for higher speeds with a 901. That it is better with a reversed H or ZD for 4th? or 5th? gear . Thoughts and opinions are welcomed.

Futur goal is a 915,.
Thanks

I had a flipped H in 5th with my V8. I loved it!

a flipped H is the lowest gear ratio for the 901.

aside from getting higher rpm's, it is the most popular way to get a higher top speed, though it is mostly used to get rpms down some, at highway speeds.

H runs about $300-$400 typically, plus install.

The 915 is not favorable in my eyes, and I will tell you why, if I may.
~
A properly prepared '72 911 down shifting into turn 17A, after a long straight, spun
ass-first and then nosed into the inside concrete wall at 17B.
One would think, rear-end went light from throttle-lift oversteer.
But no, the 915 engaged the two downshifts into 3rd normally, without event.
In the short distance between the turns, the 915 seizing two gears, instantly
locking the rear wheels, causing the 911 to polar shift just before hitting the wall.
~
I was driving in a clump of law-abiding traffic in my '72 911 South of Jupiter,
on the turnpike. The sun was bright, suspended in a clear, blue sky,...at first.
After a move around a box truck, I returned to the right lane watching the
70mph log of traffic being consumed by a fast approaching, dark and menacing, rain wall.
Brake lights, traffic compresses, I down shift into 4th, still in the dry, with a 50 yard
squench factor between me and the other car ahead.
At first, I thought someone hit me in the rear when my car went sideways.
I pushed both feet in and steered hard left, onto the shoulder.
The rain sounded like a waterfall of marbles as I quickly looked around and checking
the gauges after coming to rest.
Engine idling, pressure good, electrical good, no strange noises. I placed it into
neutral, and lifted my clutch foot. It lurched forward and died.
The 915 was locked in 4th, clutch not functional.
I started it engaged in 4th and slowly matched the speed of the traffic before merging
into the right lane. I drove it home, 60 miles like that.
The only sign previously, was a whine that had developed at the low end of 2nd,
just days before.
~
I haven't trusted 915s since.

Driving near Jupiter and closer to the gravity of the sun is a sure fire way to screw up a normally functioning transmission.

Racing downshifts.....to much stress overtime.

The 915 is still stronger than a 901 any day.

To the OP, go search Carquip.
He has all sorts of gear sets online for sale.

Rich

Thanks
I was thinking of going flipped H.
Just wanted to see what others thought.