I was wondering if what I heard is true. Can you grind the exhaust valve guide boss down to the roof of the port? Some one said by doing this it will improve the flow of the gases out the port exit. I already have one almost to the port roof. But, I didn't think to ask if it would cause any problems with the valve stem or guide. Did I **** up or what? Here are some pics of the one almost complete and one I haven't touched yet.