Upgrades
 

What have you done to your f4i that is reasonably priced that has made a good performance difference?

I have already replaced forks, K&N air filter and 2 bro pipe. I'm thinking next step is the power commander but that is $280.

Any suggestions?

520 chain and sprocket kit with lower gearing or pc3 like you said, the chain and sprocket kit seems to do more for my bike

Did you get new or used ones? What year is your bike? Are you forks inverted or oldschool?

By the way, what do you need such performance for? You are going to gain little by little here and there, but even stock has a lot of power already.

The forks are mounted old school. I did not know that you could invert the forks. What are the benefits in that?

My bike is a 2003 f4i.

If your bike is '03 then it means that you have 115 hp without mods already.

Al manufacturers switched to inverted type of forks in '04 or so. It's better setup, but I don't think that would make a huge difference on our bikes ('01-03).

Forks is the most expensive upgrade, good new forks run from 1.5k$. I might be mistaken on this subject though.

Whats a good brand for chain & sprockets?

+1 to sprockets and 520 chain. I have Vortex sprockets and they seem pretty good and are popular, they also look great. Go -1 in front +2 in back tons of acceleration and you can still do 150. Unless you want to do crazy wheelies then go +7 in the back.

-1/+2 is already a lot. Don't go any higher than that. +7 will make a stunt bike out of yours.

The F4i has never had 115 HP. Also the 04+ F4i has the same forks as 01-03 (non-inverted). Not all bikes have inverted forks. It depends on the purpose of the bike. Most modern race-inspired sport bikes have them, but not all.

The most effective power mod you can do is a PCIII and tune. It won't be cheap in your book, but it'll get you more power for the money than spending the same amount on anything else (about $600 total depending on cost of the tune). Changing your gear ratio is also an effective mod if you're looking for more low-end torque, but it will slow your top-end, and not really give you any more power, just change where it goes.

If you try to do much more, you might as well upgrade your bike and not bother.