In my opinion I would find one with tired 525's and build your own whipple 525's. The power is great and you will get what you want. Stock bravos will not be happy so you will need to have them upgraded by either of the bravo shops who know what they are doing. But you still have to be nice to them.

So what you said above means a 525 will make more power cause the compression and cam. That makes sense.

If you are going to run around 70 mph a lot and only wide open throttle once in a while. A XR can handle that w matinence. But if you are racing or throttleing waves.. No deal

Yes, more cam and our bigger, wide design intercoolers but yes, it makes more HP and TRQ. We put the 525 cam in a lot of the 600, 662 and 700 engines during rebuilds.

Was wonder also which package was better,going with whipple525 with Imco SCX4 drive on 27' V hull,will see what happens.

Perfect post customryder

The kits come with 3" x 8" fuel coolers. All returned fuel goes through the fuel cooler which is plumbed into the stock water lines. Shouldn't be any vapor lock issues. Especially since the fuel rail is not in the center of the intake manifold like the stock Mercury 454/502/500/525 which allows a lot more heat soak and possible vapor lock issues. Returning to the tank is always a great option, but they work well without when that's not an option.

Great thread, here's my amateur input. I own a 38ft Donzi ZRC. I bought it with stock 525's and Brovo XR ITS drives. I really had no idea what the ZRC really was when I bought it but quickly learned the hull was legendary winning countless World Championships. It handled marvelously and though it did about 90 I could tell it had much more to offer speed wise. My mechanic Nick Oliver from Offshore Performance one evening said I was right and should look at Whipple Superchargers. Not really knowing what I was buying I ordered a pair of blue Whipple Stage 2's to match the Shelby Blue ZRC and Blue stock Mercury Racing 525's. First of all on the cosmetic side the blue Whipples on top of the staggered 525's and chrome CMI headers is a sexy as it get's! The Wow factor when you open the hatch is something special.
Once I took it out for the 1st time I was shocked how fast my boat became. I took it to the Winter FPC Poker Run and stole the show. I then took it to the Miami Boat Show Poker Run and once again out ran just about anyone in a V Hull. I easily out ran Cigarettes, Outerlimits etc from 30-90 mph. I was ecstatic how well she ran. I did experience my first vapor lock incident when trying to leave Sundowners in Key Largo. After countless efforts not knowing why the fuel filters were not filling up I decided to remove them a second time and walk them to a marina next door. Luckily they had 91 octane fuel. By the way the engines really prefer 93 octane over 91! Anyway I screwed them back on after topping them off with fuel. It cranked right up and the problem was solved with a little help from the patrons. Remember I was running stock Mercury Bravo XR ITS drives. On the way back it decided to take the Ocean route back after dropping a few friends at Hualover for my journey back to Delray. The ocean was a little choppy but ran the boat hard. It ran marvelously and caught air I guess a few to many times for the XR's to handle. Remember now I'm pushing 825 HP out of each engine. Just as I was pulling in my canal my port engine stalled. I couldn't get the engine restarted as the shifter was jammed in the forward position. I couldn't get in neutral. Anyway I got it on the lift with one engine then called Nick the next morning. I had gotten about 50 hours up to that point with the Whipple's. The adrenaline rush up to that moment was fantastic. The bad news was I totally wasted the port drive with pitted gears, black gear oil though changed before the run and a twisted shaft. The starboard site though still functioning was also bad. I love my boat, despite the Donzi name taking a hit I think it's Bad Ass. I don't know of another V hull currently offered I would trade it for. Bottom line is I wanted it fixed now! After consulting with Nick and Brian from Offshore Outdrives we decided to go with the IMCO SCX uppers, upgraded stronger shafts and new gear in the stock XR ITS lowers. I personally spoke to the owner at IMCO. He's a great guy who instead of trying to sell me IMCO lowers as well explained I would probably lose 7-10 mph if went with their lowers. No way in hell was I going to do that! Bottom line is Whipple Stage 2's on 525's rock. Insane fun factor and on my 4 step super light 38ft hull outruns even boys running 1050's with heavy competitive makes. The look in their eyes is priceless when I blow by. I get the new IMCO uppers and shafts along with the gear set this week. I'm being told I make actually pick up a few miles per hour with this configuration. If so I think in calm waters she will do 115-125mph range. Insane fun ahead and will advise on the progress. Thanks fellas.

DJ
Shelby Blue Donzi ZRC

When #6 drives do break...break out the big $$$

Tried sending you a PM but is full.