[QUOTE]Originally posted by THE GOOD STUFF
03 353 with stellings boxes & 525 EFI 87.8 gps with merc lab 33 .also ordered from magicfloat [ Speed change. Cut out the deflector plate in the mufflers with a 4 inch holesaw. Went from 87.8 gps at 5200 rpm to 5350 rpm with rev limiter going off could not really see what it really has . I did see 89 gps.I am going to try a set of 30 six blade herings . I hope to get the slip down and maybe gain 2 or 3 mph. Has any one tried the 6 blade hering yet. And could someone figure both of these slip #for me or what is the formula again. Runnig same props both times .My gear ratio is 1.50. QUOTE] Thanks Rex

The Good Stuff is right. 525's don't like mufflers.If you(and the local authorities) don't mind the sound,there is a decent speed increase. I think John B also had a similar gain.

Rex,

My calculations have you at 20.15% prop slip running 89 mph @5350 revs with 33" props. If you would like I can e-mail you a simple prop slip calculator I wrote in excel.

Double Dealin'

Went for a ride on this boat and now the motors are freshen looking to hit 105 mph.
http://www.offshoreonly.com/forums/s...threadid=50963

tesheer , That would be great.. Thank you for your help. wildthing , That is hauling a$$ in a 35 . Was the boat real stable or was it side to side like it was running out of boat to run on. Rex

THE GOOD STUFF,
It was pretty stable, no chime walking. After about 85 the boat was airing out real nice. He is going to try some new 5 blades then maybe some 6 blades and did more head work. This year it should really scream.

My budies 353 runs around 75-77 he does not have extension boxes .Also it's a 98 with carb 500's

Can anyone confirm the 2000 year X-dimension up 1"
Really curious!
Thanks,
MD

Re: 353 Fastech How fast ??
 

just got a 2002 353 with 500efi no boxes and xz drives from nelems marine in AL about 3 weeks ago finally opened her up this weaken hit 78 with 8 people on board at 4800 rpm so she probably do 83 82 with just me and my son on it .

Re: 353 Fastech How fast ??
 

That speed not GPS with 8 on board?