Put out max at all times. Don't hold back. If you've got a high 1st class already (18min. run and 20+pullups, plus however many crunches) then give it all you've got! Yes, improvement's very important IF you've got room to improve. Make your "overall" package look good and run with it! Concentrate some of that energy you'll be saving by not struggling to achieve that high PFT score and put it to doing some extra-curriculars! You've got the wrestling bit going (Marine's LOVE aggressiveness), do some community service or something else that'll look good in your package.