the shorty headers provide almost to no gain in performance. i think it was measured in the 1-2 HP vs a SVT system that is still 50 state compliant that can add 15-18HP
$230 for Cat + $180 for Shorty Header = $410. SVT header, Cat & Flex are selling for about $350 in the for sale section. left over money would cover shipping costs and the SVT dip stick and other minor things you might find.
FS: SVT Header, Flex Pipe, Dipstick Tube