intercooler won't be good for 500 either (this info comes from someone with first hand experience)... I'm already looking for alternatives (and/or Aquamist) and the 3 to 1 tubing needs to be redesigned as the current one is really poorly designed, even to my untrained eye
wrt to the piping, there's powdercoating and powdercoating mate The PE one looks cheap (even when the components aren't by any means!), I've had mine powderoated gunmetal silver, looks miles better.
WRT dynoing, tbh I haven't seen any in the US either (apart from an old magazine article which compared different types of turbo kits for the 350) so it'd be great to have some real life figures from yours. As I said I got my kit because of the great deal I got, and because, despite being quite incomplete for my tastes, it ticked all the boxes for my goals (500bhp for a cool running, useable 350). Anything more and it's just for bragging rights IMO, as you won't be able to use the power anyway...