Those who've driven the 1.6 Altis have probably noticed an irritating noise from the firewall - this is noticeable under mild to medium acceleration.
Then there is a very significant resonance from the exhaust between 2000-3000 rpm, and it's especially irritating if you're cruising in that range (ex. 100km/h)
I've checked multiple cars and all seem to have this problem. Do these cars have a catalytic convertor? I know Euro II was just implemented, but I think since the face lift, these cars probably come with one. I haven't had the chance to check under the car physically.
IF this is so, this could very well be the problem. If someone's seen the exhaust in detail, is there a bolt on connection after the headers/downpipe? before the cat? Also, any different in sensors on the exhaust for the Xli/Gli?
In short, would it be possible to use an Xli/Gli exhaust system on the Altis?