I am 99% sure Im gonna go with the Super B ( not super b special because I tow). with my setup now if i put my plate all the way forward I Spike 48 lbs at WOT on the hx 35 with adequate black smoke, and a quick 1300 degree egt reading. I have the plate back to hit 36 lbs wot throttle now, anyway do you guys think Ill see a big power gain??? And Ill finally be retiring the straight 3 inch to go with a straight 4" stack. If I dynoed 300 RWHP what might I be able to achieve with the turbo upgrade???

 

The turbo will give you more useable power. You already have the power, you just can't access it due to high EGT and lack of air flow. Its hard to say what the increase would be on a number, but you will be able to hold WOT with the plate forward for alot longer. But with the Super B that addition of the 4" pipe will be a double whammy drop in EGT and increased flow..

 

Save some money ($200), and get a HTT 62/14. Its a great turbo for towing. And has room to grow into. You can always send it back and upgrade it for a couple hundred bucks.
Check out High Tech Turbo.
Bd-power is WAT overpriced on their stuff.

 

I looked them up, the 62/12 says it will run well between 450-525 hp. think I can feed that? Im thinking about putting a #5 plate in before DV's or Inj.

 

Either the 62/12 or 62/14 would be a good choice. The 12 will spool faster than the 14, but the 14 will cool better on the top end than the 12. I think its only 150 to 200 degrees cooler.
I would take your #10 plate and turn it into a #100 by grinding it yourself.
I think you can fuel either turbo. Especially with the #100 plate full forward and the afc full forward. If its still not enough you could always do more afc mods for free.
If thats not enough you can always get injectors.
You have the tranny. to do whatever you like.
The search option on here is your best friend.