bardup

Hello All First Post long time browser, so go easy on me. I have a Barcrusher 560C with a 140hp Johnson outboard and have a problem with trimming the boat. The boat gets up on the plane easily but after travelling 100 mtrs or so then decides to noticeably "dip" to the helm side. This has happened since new and we now have 20 hrs clocked up. We have done all manner of things to balance the boat even emptying the bait tank thinking the weight on that side might be a problem, even had three hefty blokes stand on the opposite side whilst underway all to no avail. We sent an email to Barcrusher and to his credit Peter Clelland responded with three possibilities, balance, wind and as a last resort fit trim tabs. Ruled out balance, wind....even on calm waters with flat water still do's the same thing, trim tabs my thought was if it needed trim tabs Why are they not fitted as standard? and if fitted.... Wouldn't this put more pressure on one Tab than the other? Making it more susceptable to possible failure? We have noticed that if you remove the bungs from the bouyancy tanks either side of the keel the air is expelled under pressure. Indicating no leaks... But.... Would this increased pressure possibly make the boat lean whilst underway? Has anyone else had this problem? and Been able to solve it? Any help or thoughts would be appreciated Bardup