Im going to build som twins for my truck 99 24v Itow alot with this truck between 5000 & 8000 feet of elavation lots of mountains. Im thinking on going with a hx35 12 or 14 exhaust housing I have them both, as far as the lower turbo Im thinking of the HTB3 or the BHTB3 in a 22cm exhaust housing what the difference between the two wich should I use? What should i look at spending on one, wheres the best place to get one? what is the cummins part number for the HTB3 or the BHTB3? Any othe help would be great.