Why does Mike not respond?

if you meant Hummer-philip, yes that is my son.
oke, I have complete faith in Mike, which it comes well.

I've bought quite a few things from Mike in the last year, and currently he is working on a huge project for me.

I can tell ya that Mike is ridiculously busy 100% of the time. Sometimes it can take awhile for him to reply but try to not let it bother you - in my experience Mike is very customer driven, in my opinion that is why he is so successful. He isn't replying to you because chances are he's working his butt off to ensure the multiple guys ahead of you get the best attention he can offer. When it's 'your turn' you will find he goes well above and beyond what you would expect of most other business owners.

~bt