I have a 1985 cali model that used to have the trap on it - until I researched options just as you are and decided to get an intake and exhaust manifold from the junkyard for 100 bucks and converted it over to the older style without the trap.
My fuel mileage went up by a solid 2 mpg and the turbo spools up more noticeably than before. It seemed like much less of a hassle to get the older style, non california type parts than fabricate a pipe.
Thanks, Adam Bush