Ported TB gains with FI
#2
very little hp gains.. guys run stock LT1-LS1 and up with stock tb's pushing 800hp or so. i just sold my blower and had a 58mm TB on my LT1. no clue if it made any difference really maybe 5hp gain which is lost in the valve train and having a auto car more lose. i would port your's before i would buy a aftermarket one.