I think alot of people forget that these arent off the shelf 64/80 turbo combos, were talking billet wheels in the atmospheric turbo, and modded vgts
Tadd takes a vgt, it gets a new exhaust wheel/shaft, which is bigger, so now you must take the ehaust housing and modifiy that to work, same with the vanes in the housing as well, and then the intake side must be modified to run a s300 style compressor housing, which is no easy task since it goes from a vband housing to a bolt on style housing...
I know what mine COST, and it was NOT cheap, just that turbo alone was almost 3k...
Ok sooo thats the high pressure turbo
how do you get exhaust energy to the low pressure turbo? Sounds easy right? Not when you have about 3 inches of space between the turbos, oh and dont forget you need to plumb in a wastegate in that small space... tadd cast an outlet to adapt from the factory exhaust housing to a t-4, with a wastegate inlet already built in.
Ok now for turbo's you need something thats going to fit in the valley, and flow a decent amount of air. Tadd chooses to use precisions, great turbos, pricey, but worth the money.
Here is a link to the turbo thats used... you might understand where some of the cost is starting to acrew.
http://www.precisionturbo.net/Stree...Street-and-Race-Turbocharger---PT8285-CEA/284
Now im going to move on to personal experience
You can rack up 300 bucks in bends for piping, vbands in no time, i spent that and i already had about 5 different vband assemblies on hand, and i have used every bit of that and then some on my build,
Then you have oil lines, which arent cheap, not expensive but mind you all of this adds up, plus you have to do something different for the oil drain on the low pressure turbo, you have to tie into the factory oil supply for the turbos, then you have air filter piping, intercooler piping, pipe between turbos, wastegate piping ect.... it all adds up to serious money. i dont even want to know what i got into my current set up, and i reused a ton of bends and piping to make it happen...
Now look at twin turbo dodge set ups, your 3500 bucks to use your STOCK turbo
your an easy 6k for a complete 64/80 kit
Duramax's are even more $