Well, I finally got around to putting on the Yoshimura RS-2 Slip On.

I combined this with an FMF Powerbomb Header and DEI 1in black Exhaust Wrap.*

*For the exhaust wrap I wasn't actually after any kind of performance increase. It's just I keep the bike covered in the city and the cover always melts on the front of the header leading to an ugly pipe and a disgusting smell.

Here's my review:

Power - Meh
I actually don't notice much of anything below about 7000RPM. There appears to be a bit of a boost after that all the way to redline, but honestly, it isn't very noticeable. The difference from the 13tooth front sprocket is more noticeable than the pipe. I haven't dynoed it and don't really plan to so you can take my word for it. The negligible power increase is consistent with the 2-4% increase quoted by Yoshimura in this thread

Sound - B+
The sound is really fantastic. Gone is the middling tuk-tuk at idle replaced with a distinctly serious gurgle. All through the rev range it sounds like a much faster bike than it is. It's loud, but just on the right side of annoyingly so.

Looks - A
The stock exhaust looked like a matte black soup can. The Yosh looks great! Fit, finish, and detailing is all top notch. It's the nicest looking thing bolted to the bike.

Weight Reduction - B
It's 3 pounds lighter than stock which brings down the dry weight of the bike by a whopping 1%. Granted the weight is mounted high on the bike. A better rider than me might notice a difference, but I can't say that I do.

Installation - A
Installation was a breeze. The hardest part was getting a good tight wrap and dealing with fiberglass splinters, but that's hardly Yoshimura's fault. They even included a spring hook for the exhaust springs which you can reuse if you ever need to replace a kickstand spring. Also, there were stickers ... so .. many ...stickers.

Conclusion:
If you want a better sounding and better looking bike and you have money burning a hole in your pocket then go for it. If you're expecting a huge performance increase your money is better spent switching up your gearing.

Update -

Power (with stock header) - B-
After much consultation and a recommendation from KLXster, I removed the Powerbomb Header as it is apparently not compatible with the Yoshimura exhaust. I put the stock header back on and there is a noticeable increase in power - especially at the low end. I'm still not doing roll-on wheelies in first, but the bike is peppier down low. Now to figure out how to update the stock fueling.

 

To get the performance offered by your exhaust, you'll have to get a tuner, pull off the airbox lid, and dyno tune a proper fueling curve.. 1st gear power only wheelies and redline "power shift" wheelies - 1st to 2nd - are the usual results..

 

 

 

If I can't find anyone in my area with a tuner, do you think the KDX 200 snorkel mod would help? It looks more open than the stock snorkel and according to this has promising results on the EFI KLX with the stock setup.

https://corecatcher.wordpress.com/20...i-snorkel-mod/

 

I believe the KDX snorkel is less restrictive. You could just pop out your stock snorkel and see how it does. I have mine out at the moment and was thinking about getting the KDX version.

Toph

 

I was thinking about leaving the snorkel out, but got paranoid that water and/or debris would fall in there as it's been raining a lot in my area lately. It looks almost perfectly designed to collect crap with the snorkel out.

 

I have had it removed for a couple months and so far the airbox looks pretty clean. I understand your concerns though

Toph

 

You can only get a little extra power with a snorkel delete /completely removed. The KDX snorkel is only good for owner satisfaction, no real increase of power possible.. Lidless allows for the possibility of 24 hp..

 

I got some stainless steel mesh and a spare airbox lid and epoxied it to the underside. Hopefully this will satisfy my paranoia about keeping debris out of the airbox. It looks pretty clean from the top too.