i might buy one of the holley or the bbk throttle body and wanted to know how hard it is to bore out the manifold? is it? or what is it that i need to make larger? i herd you have to bore out somthing to get the 58mm on there cause its normaly stock at 52mm?
will ther ebe a diffrence between the 58mm and 52mm?

 

Making the manifold throttle body bore larger is no big deal. All you need is a rotary file and an electric drill motor. Use the gasket as a guide and try to be neat so it does not look like a rodent did the work. Keep the shavings out of the intake manifold. Stuff a rag in there first, and then vacuum the shavings out when you are finished. The larger throttle body won't make much of a difference unless the engine is modified and can use more air than the stock throttle body can provide.

 

x2

 

x2, you're not going to get any real gains out of a 58mm TB until you're making at least 350 RWHP, maybe more around the 400 range...

 

do you have as LS1? if you do it is much easier to unbolt the intake, then to worry about blocking chips from falling down into the engine, but you really don't need to do any of that because it really isn't going to give you anything noticeable with your seat dyno