If i were you dude knowing when we've spoken about your spec i'd stay with the .48 housing and Karl's map, yes you'll get abot more from the .55s and the .63m BUT i know you like the punch the .48 gives you.

Try CR Turbos for a new one or Turbo Technics..

Probably looking around £800+ though...

My RB T35.55 was over that...