intake/exhaust mod questions

Just out of curiosity today I pulled off the door to the airbox. Rode it around the neighbourhood and felt like I gained quite a bit of power. I only ride on the street so I'm not concerned with water, is my bike running dangerously lean right now? I don't want to risk frying the piston.


At this point how much extra power would a header/exhaust give? Also, has anyone tried the resistor trick on the intake air temp sensor, fooling the ecu into thinking it's cold out and richening up the mix? Does it work?

I don't want to drop a lot of money into a power commander and full exhaust for this bike. I've done it with every single bike I've owned and it's getting kind of old. Has anyone tried gutting the stock muffler, sticking a perforated core/packing inside it to turn it into a glass pack?

Finally, I haven't gotten around to taking apart the exhaust to have a look, but is it a 2 piece design? Header and muffler? I want to get rid of the exhaust valve and the cat, so only want to replace the section that houses these parts. I've also heard of a lot of people removing the AIS system. Isn't this system only for injecting air into the exhaust to burn off raw fuel? How will removing it improve performance besides dropping a bit of weight?

read this : http://www.wrrdualsport.com/tech-guide/dynotesting/71-dyno2

The exhaust is a two piece system. The cat and EXUP crap is all contained in the muffler.

A slip-on exhaust will be your best bet and is cheaper than a full system, but you will need an EFI unit.

Someone has gutted the stock can, but that was over at Thumper Talk I think. Personally, I don't think that's worth the effort. The stock can is not something you can disassemble and reassemble.

Are you running "dangerously lean"? I don't know.

Modifying your intake (free mods), adding an EFI programmer, and adding an exhaust slip-on should net you 3 to 5 horse power from what I've heard and read.

Roughly a 10% increase in horse power.

Don't fight it.
If you're already removing airbox doors and test riding the bike looking for more, do it right and modify the airbox and get the fuel injection programmer and get your new muffler.
The bike will run and respond to the throttle much better.
To top it off, the exhaust tone and volume will be quite nice with the popular FMF Q4. :)

Typically, when someone "wants to save money" and guts a stock muffler, it ends up sounding like the bike has an exhaust leak with a shitty tone and kinda' loud.

I just installed my FMF Q4. It sounds really nice! The install went very smooth no problems whatsoever so just for fun I pulled the airbox door off and took the bike out with that combo. WOW! What a seat in the pants difference. It just pulls!

There is one thing. With the door off the intake noise is loud. So now I am wondering is the Airbox Flapper Mod just as loud or would it be slightly quieter?

Oh yeah did I say I just love riding that thing! Hmmm??? Maybe a fuel programmer next!

The flapper mod is basically a stock airbox. Most of the time its already open anyway, you just make it open 100% of the time with the flapper mod.

Flapper mod is quieter...removing the airbox door is awesome.

(assuming you're not riding in dirt or possibly submerging your wr.... )