Help please, Have Mazda E 2000, flat tray 2003, with 12" rear duals,
4:1 Diff. It is slow on Highway, looking for 14" wheels to fit or higher diff ratio, have fitted Bravo 2.5 Turbo diesel engine.

It is a great little truck, we use it with a slide on camper and a general run about vehicle.

Cheers.

 

Your vehicle is a beast. It is tall, long and squarish.
Your engine is small. It's no wonder you have no speed.
I would not want to drive that thing fast especially on highway in the wind.
Changing to different rims with same height tire will do nothing.
Putting on taller tires than stock may give you more speed for same revs, however your speedometer will wrong and reprogramming computer will be necessary, and your power will be reduced, hopefully no suspension clearance issues. That big beast needs those hi revs due to it's boxy and large shape and because of small engine.
Good luck!

 

The truck is a single cab flat tray, with a 2.5 Bravo turbo diesel engine fitted. It has plenty of power, but the ratio is too low to give me top end speed without over-revving. It is beautiful to drive and handles perfectly, except for this issue.