Has anyone upgrade to 2 or more piston calipers is so what did you used and was what else did you need.....I want to get some ls 400 brakes but it might not fit.

 

What are you trying to do? Just upgrade the calipers, or rotors as well?

Here's a link for a pieced together BBK.
http://clubsciontc.com/forums/suspen...ly-done-49348/

 

Am i correct in that a company (Wilwood?) makes a caliper upgrade for the tC1 that works on stock-sized rotors?

 

You're correct, but the price

http://www.fastscions.com/wilwood-4-...2005-2010.aspx

edit: Also remember just upgrading the caliper with more pistons doesn't mean stopping distances would decrease. You have to consider tires, rotor size/diameter, brake pad material and contact area, brake force distribution, etc...