Just because it gives me something to realistically aim at.... I just like trying to get stuff set up so it performs to the max.... If you can help me get to 60.... then 60 it is
Yes even for me 158mph seems a little over specced!!!!
2005 Zodiac 5.30's were rated at 100HP, but the 2006 model is 115HP... as as my dealer helfully pointed out when we where purchasing... the 140HP is lighter
Boat hp ratings are not just about weight of engine - but as much about the torque and power of the engine trying to rip the transom off as it trys to push your boat along.
If your dealer sold you a 115 rated boat witha 140 on the back then i hope it will be him that will pay to get the transom fixed when cracks start to apear as i doubt zodiac will be interested !!!!!
I have no real worries, as the torque of the 140HP is very much in line with the 115 on which it is based.... it only develops the higher HP further up the rev range.....
Also the transom is built with huge layup!!
I had a 4.8m Yachtline for 4 years, it's max was 75 and we never had a seconds problem with the 90HP yam on the rear of it. If fact that was a superb boat and still available to buy from my dealer i think.
Drop a match down it's tank!! 
