change rear end ratio or change transmission

Choose one;
Pull hills. Lower gears (higher numbers) will help, but limit speed.
Higher speed. Higher gears, (lower numbers) will help but limit pulling power.
What rpm are you turning at 72mph?
I'm turning 1500 at 65 with a 10spd and 3:55's.

 

No matter the gearing , how fast you can go up a hill is solely reliant on horsepower.
Modern 18 or 13 speed have same ratios at least in top three gears. Your 1998 may have different ratios if your can find the model number of your transmission.

 

Gearing is for speed and startability. Horsepower is what gets the work done.

 

95 379 S60 - I went to 3:55 from 3:70 on 24.5 LP - 13 speed.

Was 65 at 1500, now 70 at 1500.

I like it better, because I can run 12th at 1500 for 60mph, or 13th for 69-73 comfortably.

Lost a little’climbability’ - I wouldn’t go 3:36.

Aren’t 11R 22.5 almost the same as LP 24.5?

 

My thoughts too. Get the numbers and check, but at least the top 2 , direct and over, are probably the same.

You’ll get a lot of life out of the engine easing it up the grades, and rolling on the flats, shifting and watching boost and pyro, than you will mashing hammer.

 

If you're "topped out" at 72 and only 1650rpm, all your limits are not taken off. That motor should turn up over 1850.

 

Sounds like a stock 550 lo-nox file. You need to find a pre lo-nox file or have a custom tune installed. What Hp rating was the motor from the factory?

 

Close enough you can run them side by side and 5 MPH slower than an 11 R 24.5.