I was reading the posts on BIM/BBTBs and did some research around me and found a machine shop that will do it for cheap. Is the only thing bored on the BIMs in the chain topic that main cylinder or are they also boring the runners as well? Also does boring the TB achieve the same effect as a larger aftermarket TB? Thanks

 

Yes, the intake hole, and the runners are bored out. And I'm pretty sure it's the same thing, since you buy an aftermarket TB to have a bigger one, and that's what boring does, is makes it bigger.. so I think you're good to go! Just make sure the shop knows what they're doing.

 

Get both the IM and TB done at the same time so that they can be mathced to the same size.

 

If you buy aftermarket (recommended) give them the TB to match port it to the intake manifold. If you can avoid boring out a TB then do, otherwise its a cheap alternative.

 

Would it still be worth it if he could only bore the main cylinder and not the runners or would it be more work than its worth?

 

To be honest, no one has tested just a BIM bore job vs the gains of a *onpol* job which gasket matches the runner openings, and also polishes the last 4-6* of intake runner.

You'd have to do a back to back dyno test (same day, same dyno, same car) for it to be valid.

My guess is that it doesn't make that big of a difference until you start getting fairly serious with the N/A mods. For just the usual bolt ons of CAI, BTB, BIM...I doubt it would make more than 1-2 HP difference.