I have 300 hours on my 1999 Formula 353. Should I be concerned with changing out my valve springs? Should I leave the heads on and use compressed air thru the spark plug holes? I've already asked which springs to use on another thread so thats been answered. I'll probably email someone who has some of these answers and ask more detailed questions about the procedure and valve guide replacement. Thanks for help.

Yes you should be concerned and plan on changing them ASAP. Can almost assure yoo that you will find some that are broken.

Do a search on the topic. You will find hours of info and reading!!

Mark