Using a dremmel tool what is the best bit to buy to perform the job?

 

You might want to just look into having a shop do it. I spent $20-30 on a good bit for my drill and it took me a damn long time to do it. I'd much rather just pay $50 or something to a shop to have it done.

 

ugg... another dremel... and a bunch of bits... or if you have a air compressor it should not be that bad. But if you are just cutting the front where the TB mounts... then a dremel and some of those round sanding wheels should be good... how many? I do not know. I would say 8 would be a good start. Most likely more....

 

Your best bet is to use a drill and 1.5" or 2" sanding drum. This will allow you to keep the holes in round and also speed up the process over using a dremel.

It's soft metal, sanding drum makes pretty quick work of it. I spent about an hour doing mine.

 

A Bridgeport-type mill with a boring head does a great job. A good engne shop will have one.

Doing it by hand, I'd use the 1-1/2 inch sanding drum. Mark it careful and try to stay within the lines. Wear a dust mask or respirator.