MUST
If you're into sport riding, the mod that will make your riding experience more exciting is a full system exhaust. It will make the bike feel noticeably lighter and sound a lot better plus you get a few extra hp on top. No loss on the bottom I can feel. A PC5 with a good map or a flash WITH fuel mapping is always a wise thing to use with a full system though I don't know that it's a must. You probably will not get your best hp without something to match your fueling to the increased flow of a full system. Some flashers are even recommending thew use a PC5 even with their flashes.
A high quality quickshifter will also add to the experience but I would suggest you go all out if you're going to do this mod. Spend the dough to get one that will shift as sure as clutch shifting or don't bother with it. The HM GP is probably a good one or one of the electric shifters if you are more into straightline high speed. Be prepared to fork over 1200 dollars or so but the excitment will be worth it.
A 45 tooth rear sprocket will make a palpable difference for acceleration but it is not much different than downshifting one gear. It's a kick in the pants for first gear though and changes the feel of the bike overall.
Lightweight wheels. Carrazeria or BST. Rotobox is supposed to be very good but they are ugly as sin. The bike will be more flickable at high speed and accelerate a tiny bit faster. My feeling was that the decreased gyroscopic effect was somewhat unnerving in a corner. The bike feels less planted but I got used to it after two years.
200/55, 190/55, 190/60 rear tire. The few extra millimeters of ride height in back make a noticeable improvement in cornering. The bike tips in much easier while still feeling stable and controllable. I like this very much and I think it is better than the lightweight wheels for handling.
Remove as many unnecessary parts as possible. Replace stock parts with lightweight aftermarket parts. After the first big weight reduction of going to a full system, no weightloss mod on its own will make a big change but after you have done enough of them, the bike handles better. It will never handle as well as a literbike.
Turbo or NOS will definitely make a noticeable difference.
MAYBE
A flash from a good tuner. Most people love it. I haven't had my ECU flashed but my opinion of tuning by modules is that the performance gain is slight. It is not what I would call "day and night." A flash will do most of the things for a Gen1 that tuning by electronic modules achieves. Downside is the electronics are adjustable where a flash is hard wired. You can't change a flash unless you send the ECU back in or buy Woolich software and do it yourself.
Suspension upgrade. I have Ohlins and I can feel the improvement but my feeling is that the stock suspension is at least adequate. The forks are a bit floaty but I was accustomed to that. I don't think I have more control with my Ohlins suspension.
High flow air filter. It might add 1 or 2 hp way on top but otherwise, no change from stock in how the bike feels. I have a lot more trust in the OEM filter and use it almost all the time instead of my BMC race filter.
08 MIDNIGHT SAPPHIRE BLUE ZX-14 Now Deceased, will be resurected
2024 ZX-14R bran friggin NEW!