What size are the 04 ls1 throttle body coolant ports? The steam vent is 1/4" but what about the throttle body coolant passages? 5/16"

 

Do we need them?
The Gen4 left the throttle body COLD... Never seen one have a problem.

 

Oh its an old free mod to bypass the coolant from the throttle body so it doesnt heat up iat only needed if temps are freezing i live in texas. As well as port the 3mm ridge infront of the throttle body blade. I did this on my 98 z28 in 2009 and 99 corvette ls1. It also eliminates having that oem L hose bust and cleans up the engine bay. My 98 z28 ran great with these free mod as well as only a lid, slp headers 3" x pipe dumps and ported throttle body or the 3mm ridge removed as well as descreened maf picked up 6mph in the 1/4mph 101mph bone stock and 107mph with just those mods so maybe 50-60whp i had picked up. I had the throttle body coolant hoses on my brothers saab 9-5 06 aero bust last year while driving. Would be easier to bypass as those have potentionmeter tps 5 wires that can get hot and split after alot of miles.

I believe the two lower ports on the ls1 throttle body 04 gto are 5/16" for the coolant ports?