Matatk wrote:
I would not use a tap unless necessary. I would try a thread restorer first. A tap can remove material in the bolt hole and if it's too much you won't get a good tight seal/connection with the bolt and thread.

I have this, works well:

http://m.summitracing.com/parts/shc-9 ... MrQy5r30rsCFcxAMgod3SgA5A