Well the 1.6XSi has a nice running engine and is quick with 95Bhp compared to the 1.6GTi its quite poor cause ive got a 1.4 XSi and she has 100Bhp but yes you can get the 16v GTi conversion kit..... and de-cat pipe and a straight through exhaust just doin that gives u 5-15Bhp extra umm and there air intake is to small for the engine so it limits the engine slighty so a fat air fliter, and uprated spark plugs best to get from ebay as they are nearly £15 RRP, Obviously if you get plugs you need uprated HT leads and coil pack just with all that you could have 120Bhp maybe more not sure cause ive just done the exhaust and plugs, leads and coil pack and mine is quick as lol.
oh hi welcome to the club!