The problem obviously with ebay kits like this is the cheap chinese turbos they always use to get the costs down. I've done plenty of research on these turbos and it is scary how shoddy the quality is. Some of them are held together with GLUE... If you can weld, you can put together a kit like this sans turbo for very cheap yourself out of basic tubing. This kit does not include headers either which means you'd still have to fab up the hotside crossover which can get complex. So really this kit is worthless.
IMO either get the NPG kit or fab one yourself using a T3 out of a JY. I bet the Supercoupe .63 AR T3 would be a good match... They are hard to find though as the words been out on them for some time. Two of them make a killer twin setup for a 5.0 but I digress...
In a nutshell:
Cheap ebay kits=junk
NPG=good
DIY=good IF you know what you are doing and properly select your turbo.
www.theturboforums.com if you want a dedicated turbocharging forum.