I was a little concerned about losing any bottom end when opening up the exhaust on my 16v 1.6 4dr. I've just fitted a Tri-Y header and 2" cat back with a a single hi-flow muffler. It's all good. No major gains but it does pull a little harder and has slightly better throttle response. No increase in noise but there is a different, slightly throatier note in the 2-3000rpm range.