I'm thinking about doing some upgrades to my 1998 Honda HX CVT coupe.
First, any engine upgrades are
out of the question.

This is because the CVT transmission can't handle more engine power. Besides, the car right now does 0-60 in about 9 seconds, more than enough for freeway onramp acceleration.
Second, I wonder should I considering installing PIAA light bulbs in place of the original halogen light bulbs. I've heard that it might not be a good idea because the headlamp reflector design of 1996-1998 model year Civic are more optimized for regular halogen bulbs, and switching to PIAA bulbs may actually reduce night time visibility.
Finally, what tires should I consider once the Bridgestone RE900's I have on my car now need to be replaced. Note that I will
not go to a 15" rim (for 195/55R15 size), given that will cost way too much money for me.

Here are the tires I am seriously considering:
Bridgestone RE910 or RE92
Continental ContiContact Touring CH95
Goodyear Aquatred 3
Michelin X One
Pirelli P6000 Sport Veloce
Yokohama Aegis LS4 or Avid H4
I've heard of lot of good things about the X One, but it's definitely one of the most expensive tires around for the 185/65R14 size.
Comments welcome.