To add to the info in the links JStieger posted, the BD twins are a decent set, although too expensive I think. For what they are charging for them, they should be fitted with an external wastegate to allow for better/more fine tuning. If you can pick a set up for under $3,500, I wouldn't turn them down as the kit would be a really good value for everything you get. It is 100% complete, needing nothing but your time to put them on. However, I would hold on to my $4,600 (suggested retail) in favor of a set that has an external gate. They can surely be improved upon, but so can everyone else's. They are a very good looking set, one of the best I have seen, and require no tricky mods to install.
BD's HP claims on their web site is for useable power without EGT issues and I would say that depending on how your power is being made, that is about spot on. They definitely run a little cooler on the 2nd Gens. At roughly 500hp on my truck, EGTs will stay at or under 1300. This is with the go pedal matted to the floor for as long as I care to stay in it, and I do this a lot climbing 7 / 8% grades up to 6000ft elevation passing those slow Fords towing campers up the mountain at 35mph (I think I can I think I can I think I can :-laf ). They will make much more than that, but EGTs will be beyond useable for anything other than playing. With everything on my truck set to kill mode, EGTs will reach about 1450 with the meth on and 1480 without the meth at the end of a 1/4 mile run. Not to shabby for a 12 second truck in 4X4, rolling on 315s, and weighing over 8K with me in it and no smoke! You do the math. Playing around in town on just the TST on level 7/7 and my injectors provides plenty of power for daily driving and EGTs will be roughly in the 1100*F range and watching the pyro is not necessary.
For extremely high horsepower trucks, the absence of an external gate will hinder you. The exhaust housing on the secondary is fairly large, almost 15cm (like 14. 77 or something), and it has dual volutes, but if you are going to be pushing 600hp daily, it will be hard to keep the secondary from over spooling with just the internal gate. At max power on my truck, boost runs at 67 lbs. Dynos on other trucks with the BD twins shows that max power is found at or just over 60 lbs (like 62 to 64), but EGTs go up considerably when you run them above 55 lbs. So, 55 lbs is it if your looking for efficiency, but there is more power there if you don't mind getting warm. My problem is I'm out of adjustment on the wastegate and at max power, 67 lbs is where they want to be and there is nothing left I can do about it without adding an external wastegate. Of course, if you just want to race on occasion at 600hp, or tow at 500hp, that won't be a problem. I would guess that roughly 600hp is about all you are going to get out of them without hurting them eventually. Over spooling them will eventually take its toll. They seem to do really well, better than a lot of others, in the horsepower range that they recommend for them. If your goal is 600hp, whether usable or not, go with something else that offers an external gate.
Some pics here:
http://dodgetruckworld. tenmagazines.com/mygallery. asp?id=8701
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