hydrofoils/stabilizer question

[swampy]

I have a '86 champion 15.5' with a 75 merc on the back.After reading the posts about the stabilizers on here I got the xpr3 500(for 75-300 hp).Got it last week and went to the delta on sat to try it out and it totaly sucked!I lost almost 5 mph off the top end and it porpoised and chine walked worse than ever.
Did anyone else have this happen to them?I'm going to send it back and might get the one for smaller boats.When I ordered it(bass pro shops) I asked if I needed the smaller one and they told me I didn't and that basicly bigger was better.
Thanks in advance,Swampy

[Rod Martin]

I have the 98 mean 16 champion, put one [dont know which] on it and have had nothing but good luck with it. Seems to make boat more stable in rough water, keeps me on plane at a slower speed, havent really noticed speed, I top out at 43 gps which works for me. I have noticed that if I dont trim up quick enough it trys to tip the boat on its side. also seems to get on plane without the bow climbing to much, a great help in shallow water.