Thanks for all the info! I think I will pull them apart and have piece mind next season.

Have you scanned the ecu for run history? You might be supprised at how many of those 425 hrs were run at idle or below 3500 rpm. I too had the compression & leakdown test done before getting my 525's springs & lifters replaced @ 250 hrs and was happy at how healthy the engines were. If your 525s are maintained and not beaten on badly, I think they should go over 1000 hrs before needing a full rebuild. My old 454 mag efi was torn down just shy of 1000 hrs and the bottom end was rock solid. This forum is a great place to learn what's going on in the performance boating world, but I would suggest speaking with a Mercury Racing mechanic and getting his adivice on what to do with your 525s. Then go out and enjoy your boat worry free. Best of luck on what ever you decide.

I had a pair of 330's in an IMP with TRS's. the prev owner ran em hard, but took care of them. 1000 hrs. when I sold the boat, buyer had it at 72 mph. GPS. now, a 330 top end NEVER needs valve springs. but that is a different issue.