Dangit - I forgot to answer a lot of the other questions I have been getting...
"Hey doc, why Holset, and not Garrett or AR?"
Easy - Holset has a nice flange on it that works, is properly designed with regard to the vanes for the job, and is the BEST fit for this application. It makes big boost at nice cold temps, and that is what we want. Hot nasty charges don't do anything but rob the engine of power and overwhelm the cooling system... (Useless fact of the day: most engines create 3 times the actual power you see to the crank, having lost 1/3 in the cooling system and 1/3 to exhaust... That's why turbos are considered to be "free" horsepower...) other turbos like a Garrett off of a diesel truck may work, but don't have the proper compressor map we wanted for the build. We're trying to get reliable power here.
"How about a Wastegate? External, or internal surge?"
The Holset 35 and 40 have the W designation which means that they have a pseudo-wastegate; commonly referred to as a "surge valve" that is adjustable right on the turbo's housing. That saves a lot of cost and space! The WGA (Waste Gate Actuator) will be a Banks Adjustable, so you can tinker all you'd like.
"What if the WGA fails? Will I over boost and blow the heads off?"
Probably not since they most often break when open -- the diaphragm won't let it boost at all. I've NEVER seen one break. Only leak from a dry-rotted vacuum hose... and that produced partial boost. Right now 90% of the deuces on the road don't even have a wastegate! This means you're either lagging like a dog or surging, never really in a prime area for utilizing the turbo. It was a military design to prevent excess maintenance, but I don't think they weighed the con's too well.
Let me know if there are any more ?'s! I'm always here to answer them!