look at imco call Dave talk to him

Something you should consider is, if you are only spinning 4200 rpm at full throttle, you are over-propped by quite a bit. Getting to the right prop will help your performance aspirations in and of itself.

I have been looking for the cam specs, when I find them (if I find them I will message you)....

x2

So true! The boat should be running at 5 grand now before any mods!

I installed cmi's 454/502 etops on my fountain. They are advertised as a direct replacement for bravo equipped boats.They are a nice piece, and reasonably priced around 3,000/per set. I had a few issues getting them to work with my merc silent choice and some plumbing/fitment issues but the support I got from CMI was well worth it.

Loved my IMCO Powerflow's on my M3 502! They sounded great too.

KE wil out perform a header,,also eddie marine makes a good set..they are anodised so they will last a long time..

4200 ..... yup something deffinately out of whack .

If your motor is stock, do a bigger cam also. Full length headers work better with cams that have some overlap which allows scavenging.