Is there other mods I can do to my bike to increase its performance besides 1200 conversion kit
1200 kit will not make your bike have any higher top end speed. so in reality it makes your bike quicker not faster. you can get to top speed faster with more horsepower, but the only way to raise top speed is to change your gearing or change the top rpm range so the motor will turn faster. you can change your front drive sprocket to one with more teeth for a slightly higher top end speed, but this would take away some of your quick take off that you have with the 883 sprocket. you could do pipes, air cleaner, drop in cams , then get a power vision or thundermax to allow for better air/fuel mixture and to raise your rev limiter rpm. if you were to do all this work it would be a shame not to go all out and do the 1200 kit and head work. so to answer your question there are many things you can do to improve your performance, it just depends on how much and what kind of improvement you want. also how much you can spend to get it.
I've been tinkering with this very thing for about 9 months on my 2013 iron. An air intake and a 2 into 1 exhaust would be your cheapest route to a fast increase in HP. A power commander or fuel Pak will squeeze a few more HP out of that set up. After that, I found that a 1250 kit was my biggest bang for the buck. I went from 38 HP to 70. Your top end speed won't go up much. Maybe only 5 MPH, but you'll get there a whole lot faster. If you change your cams, you can change all that HP to whatever you like. If you want a quick 0-60 speed then try the Andrews N4 cams. If you want that higher top end speed maybe go with something like the N6. An 883 clutch only lasts about 100 miles with all that HP though. I learned that the hard way.
Pipes, air intake and brand X tuner will give you a 10% boost. BFD, 10% of 48 is a whopping 4.8 hp increase.
The only way an 883 will perform, as in quick, is with a 1200/1250 kit and a tuner such as a SEPST that will raise the rev limiter from 6200 to 7000. Now, depending on how much engine work $$, your hp will run from 80 to 100+.
A genuine Harley 1200 conversion kit includes new cylinders, cylinder heads and a whole bunch of other stuff, to make your bike exactly like a stock 1200. It is expensive. A much cheaper alternative is an aftermarket 1250 conversion kit, which uses your stock heads and simply includes cylinders with pistons and gaskets, it will also need a tuner. It really is well worth considering! To get anywhere near the same performance increase by staying at 883 will cost much more.
Use Search for '1250' and read some of the recent threads on the subject.
This is an interesting question. And as others have already stated you could just do a 1250 kit and TBH that seems to be the best route to go.
But, if you aren't interested in more displacement you can always stay with the stock 883 and modify things like the heads, cam, pistons, exhaust, air cleaner, and a good tune. I am sure the stock motor from harley is not as powerful as it could be.
I would be really interested in what one could achieve sticking with stock displacement and modifying the aforementioned engine parts. It could possibly cost less. But, you are never going to get the HP you could get from more displacement.