it has a hmf slip on, k&n air filter, jetted, nerf bars, what else can i do that wont cost alot of money and will increase performance or make it look cooler, i was thinking about makin g a straight pipe but idk how that is for the engine.

 

straight pipes are a bad idea for the life of an engine. The neighbors probably won't appreciate it either. Plus, I doubt the straight pipe will give you any more peformance than what your HMF is doing - at least none worth the down sides.

As for performance, you could try changing sprockets and play with different gear ratios that better suit your riding style. For me, I dropped a tooth on the front sprocket for more low end grunt b/c I do not race, but love to pop wheelies! So the slight loss in top end speed is of no consequence to me. Other than that, tearing into the motor to do a cam or higher compression piston, etc is about all that is left.

You could also flip the front wheels around to widen the stance about 5"- that will really help with handling. Nothing like a cheap upgrade! Be careful, chances are your valve stems will rub the calipers, so you will need to install shorter stems, or relocate them to the other side of the rim. Plus, your brake calipers will be a little exposed too. I just did this on my warrior. If you look at my 'pics of my '88 warrior...' thread, you will see what I am talking about.

 

theres endless mods to can do to warriors, straight pipes will toast your engine pretty quickly, no backpressure will fry valves and cause alot of engine heat, HMF, Yoshi Rs-3 and White Bros E-Series are the best pipes for warriors imo, and the only head pipe worth getting is the FMF Powerbomb, you can get the Edelbrock Quicksilver carb, Z400 carb, or any other 36-38 mikuni flatside carb, also webbcam makes alot of nice cams, use there valves and springs or kibblewhites,K&N pro design clamp on filter or foam filter, UM aluminum airbox or a custom one,JE 366 kit,Hot Rods 400 stroker kit, port and polish from a nearby motorcycle shop,the best way to make warriors fly if you got the time and money is the FST 446 Kit, works awsome but pretty much requires an oil cooler and a thicker clutch pack, after those kits warriors have HUGE amounts of torque more torque then the 450s but not as much top end power, even with 15 tooth front sprockets they will pull the front end up all the way to 5th easily and will spin on asphalt in 3rd gear if u just goose the throttle.

 

+1 on what they said. you might start with a piston and cam. then port and pollish

 

I don't have a Warrior, but from what I understand, it has a lot of parts in common with the Big Bear which is what I have. Higher compression pistons and cam shafts are pretty inexpensive and can make a noticeable difference in performance. I paid under $400 for the Webcam, 10.25:1 Wiseco piston and a set of valve springs. That didn't include the core charge on the cam which was another $115 or so.