i have a 2001 honda civic hatchback (6th gen model tho) with a D14 engine wot possible performance upgrades could i get that would be worth while. also i have 15" alloys on it and i was wonderin what is the biggest size i could go? i seen a picture of a 2000 civic with 17" alloys on it but it had loads of room left before getting anywere near the arches. could i fit 18"s on my civic??