Ive run dd2's, dd3's, supermentals, Mach4s, and now mach4. 5s. My original DD3's are very nice and i still have them in the garage. The 2s are pretty good, but not as smooth as my 3's. The mentals i had were junk, terrible idle, more smoke, egt's and no noticeable power increase over the 3's. I sold them after 1000 miles. My favorite by far is this new set of 4. 5's. Extremely smooth and nice power delivery all the way through the powerband. It is amazing to me how much a nice set of injectors can change not only the amount of power the truck has, but how well it runs in general. My truck is smoother with the Machs, than with the stock injectors. Now i have not had the stock turbo on this set, but from the way they run, i think it would be a real nice set up on an HO to run them with no box. I think you would have to be mindfull of the pyrometer if towing a good load, but i think they would do a very fine job. With the comp on 5x5 however, no way you could handle near all the fuel. I can get over 1600 pretty quick even with a full size B1. One of my all time favorite towing set ups on my truck was the first set up which was DD3's (100hp) plus and edge EZ, and stock turbo. I would love to try that set up with a 100hp Mach injector. For towing heavy, i do not like heavy fueling boxes like the comp, tst, etc. I Think you would be very happy with the mach 4s and just a boost fooler with nothing else. If you wanted to kick it up a hair more, you could try a catcher or an EZ. The way i see it, if you go big on the injector now, you would be all set up for later on if you decide to upgrade turbos then you could run a heavy box like a tst, blue chips or comp.