97 2.2 vs. 99 2.2

[mbeau]

I have a 97 Impreza OB and a 99 Impreza wagon plain jane. I bought them both new. They both have 2.2's and 5 spd's under the hood. The 97 developed piston slap fairly early on when cold (it gets very cold here in northern MN) but of course it goes away when warmed up. The 99 never has had it and has alway been much stronger then the 97. My question is... did they change the engine or did I just draw an unlucky one with the 97? Is the lower performance related to the piston slap?

 

BTW, the 97 has 175k on it and is still as good as it ever was. The 99 has something under 50k as I recall. I like them both but it is a royal pain in the arse to get parts and I'm not sure I'd get another one because of that.