Is it worth it........

That sounds like a good price. What transmission is in it?

You say it is a 425 HP, if that is the case it is probably a DDEC II, or a slight chance it is a DDEC I. Look at the computer on the left side of the engine and see what it says. I don't know if there are any programs for the DDEC I & II, there may be.

As far as power goes, the torque is more important that the HP. That truck is probably a 1450 ft lb engine, but there is a possibility it is 1350 ft lb.

If you could get it to 1550 ft lbs, you will tell a big difference. If you only have a 1450 transmission, most dealers won't turn the truck past that, and will try to claim the computer is not capable of doing it, but that is not true.

1450 ft lbs will do fine if that is what you end up with. The Freightliner you were looking at probably only had 1250 ft lbs anyway, so you will be far ahead in torque, and get much better fuel mileage too.

Having a Detroit turned is not a cheap thing to do. Most places are around $400.00 or more to up the program, but there are some things you can tweak in the existing program to up the power and torque that don't cost much at all, especially if you have a friend with a hand link.

 

That sounds like a DDEC II. If it is able to be set like the DDEC III and above, and it should, get someone with a hand link and set the injector response to .75 on all injectors. This will make a big increase in low end power, pulling, take off, and will help the fuel mileage.

We used to drill the fuel restrictor on the rear of the head out to 89 thousants, but I don't know if I would do it with the low sulphur fuel.

The purpose of the drilling is to let the fuel flow through the head faster, therfore keeping it cooler, which in turn makes more power, as the fuel is denser.

With the low sulphur fuel there is not as much lubricant, so I don't know if now I would be willing to risk injectors with this trick or not.

You may also be able to add an LL box to the rear of the transmission to convert it without having to buy a whole transmission.