Hey mate, best to PM lowsquire or Bugboy on this forum. I cant remember who does them, and who sells the parts for them....but they are your best bet. they can make a 4 1/2 inch narrowed with shock towers.
BUGBOY sells the parts, if you want to get it done yourself. Otherwise Ben at Rancho (lowsquire on here) builds them.....there is a thread with details if you do a search.