IMO a pneumatic die grinder works well and is easy to handle. You will need an air compressor that can keep up though (mine couldn't). I ended up going to Home Depot and buying an electric Dewalt grinder. Both are pictured in the attachment. The electric grinder is quite a handful, be very careful if you go and purchase one. Make sure you wear goggles. A couple of years ago one of the small grinding wheels (like the one pictured) exploded in my face and nailed me right in the goggles before I could even blink!
One nice thing about the 2 tools is that the various attachments are interchangeable. I forgot to include in the picture 2 different steel rotary files (one coarse and a medium) which worked very well when I was cleaning up the inside of the intake. It was noisy, time consuming work but I am very happy with how the TB and the intake worked out. Besides I didn't have any money left to buy already modded parts!
Good luck with yours!
