520 / 525 SX etc., Exhaust System Pros & Cons?

Hi All,

I would like to here all stories (good & bad) with your exhaust system experiences. Weather it be a slip-on or full system. Looking to get my fist KTM 4-Stroke (525 SX). Race 98% MX and wondering if changing the whole system is worth it or just go with a slip-on. Any Pipe reviews out there?

Thanks TT’ers! :)

Jim G.

I have a '01 520 exc. Last year I bought a big gun system. I don't think it was worth buying, maybe it's not the proper application for my type of riding but I couldn't tell the difference. It is much louder than before but power wise I couldn't tell. I only ride off road no mx. It's not a product problem or anything I just don't think I needed it.

I'd suggest getting the bike and riding it first. I just can't imagine anyone needing more power than a stock 525SX will produce. It's like these folks I see at the track when I'm working on the club HS. Big dollars everywhere on a super tricked out brand new CRF450, YZ426, etc. And they don't even go for the doubles or any of the big stuff. And then some kid with an 8 year old YZ/CR/KX/RM250 or, better yet, an 80, is getting huge air. I just don't get it.

Big dollars everywhere on a super tricked out brand new CRF450, YZ426, etc. And they don't even go for the doubles or any of the big stuff. And then some kid with an 8 year old YZ/CR/KX/RM250 or, better yet, an 80, is getting huge air. I just don't get it.


And quit talking about me... I do SOME of the doubles! :):D

To the topic at hand - I see a bunch of guys running the Pro Circut T-4. No so much for the extra boost - more because it's a cheap way to dump a few POUNDS from the bike!

The only sure bet is the akrapovic, 5.8lb loss and 5hp gain across the board, it aint cheap however. :)

Arkmx, i just bought a 525sx and i feel it has plenty of power. I have heard great things about the akropovic full ti system. I was just at the Del Mar mile, and the guys who were running in the pro singles class had akropovic systems on there ktm rfs's. I was thinking about buying the system, mainly to save weight, there isnt really any need for more power, especially since the 03 sx's only have four speeds. I think i would look into the six speed conversion aswell. :)


It is fair to say that the 525/520 bikes have more power than most people know what to do with, however, adding a new pipe will most certainly change the way that power is distributed.

I purchased the Pro-Circuit T4 pipe for three reasons:

1. It significantly reduced the weight of my bike.

2. It has different diameter end caps which allow you to tune the bike for different applications.

3. At around $250, it's one of the cheapest aftermarket pipes available.

I've noticed significant changes in my bikes power delivery with the new pipe. I run the 2" end cap on long, wide-open tracks and the 1 1/2" end cap for tighter tracks.

It's definitely worth looking into if your looking for a simple way to modify your bikes performance.

One additional added benefit to the T4 pipe - Pro-Circuit states there is no need to change the jetting. Just bolt the new pipe on and your good to go.


2002 520MXC

and 5hp gain across the board

Is this a manufacturers claim or an independent test result? Please let me know where I can read about these results. 5hp across the board is amazing. I still maintain less than 1% of riders could use it but that's one heck of an increase.

I have run the stock, T-4 and the SXS Akrapovic systems on my 02 520/540 EXC. The T-4 saves weight and improves performance at a reasonable cost. It is loud too loud for me so I sold it. The Akrapovic complete system is IMO a truly great system it improve the response across the powerband and flat out rips. The Akrapovic system I purchased was the Ti silencer and SS header/exhaust pipe version. It still saved 5.4lbs over the stock EXC system. The bonus too me was it is only slightly louder that stock during normal riding conditions and much quieter than the T-4. I had a SS screen placed across the end of the exit pipe in front of the end cap as a spark arrester (but not USFS legal). My only issue now is in California after Jan 03 the 96dB sound law (public lands) goes into effect and I really want a USFS SA. I'm working to solve these issues as I love the system. Fit and finish can only be described as exceptional.

Jeb don't know about 5hp ACROSS the band but it has plenty of beans across the band at a more reasonable sound level than almost all of the other stuff.

As you can tell I believe its a great system but it is pricey.



Clark, I just saw in the AMA District-37 news letter that the dB limit was set at 98 dB with a 2 db tolerance. So you could be as high as 101 dB and "pass".

Here's a link to it : http://www.district37ama.org/offroad/newsletter/oct02.pdf


That was interesting reading. Today the limit where I have been tested is 99dB but they let you by at 101dB. I not sure how all this is going to shake out. But one thing is for sure it will be a pain. I for one appreciate the move to quieter exhausts and I know a good quiet lighter weight exhaust can be made and there is a market for such a product in off road / dual sport. I just wish the USA companies would take up the challenge and design one. The Akrapovic with a simple end cap change can be made quieter USFS legal still be light weight and have plenty of punch--not quite as good as the open end cap--still a significant improvement over stock and a large weight savings.

Thanks for the link


I bought my T-4 for all the reasons Justin states, but I agree with John (JEB) that you should ride the bike before making that type of change. I am assuming you have already ridden one and feel you need something more.

Some have this sense that the better rider you are, the more power you need. That does not seem to work out in reality. While it is true that you have to learn to walk before you run, some really good riders get slower with more power. Some really slow riders get faster with more power. This is a question and riding style IMHO. I found the T-4 gave my 520 more power delivery where I could use it the most, making me a bit faster. Taking that a step further, I am faster on my 520 than on a 400 because my riding style focuses more on the low-end power to overcome obstacles. At my level of riding, the 520 is more forgiving when I do not properly prepare for a woods situation, yet rarely is it a handful (the mud is the only time I get worried about the power, but that's true of most bikes). Others find just the opposite - their riding style is just different. Of course, it could just be that I need more riding lessons :)


Glad you liked it. :D I too hope the US builders will "step up". I know in my heart that "less sound = more ground" is true. One of the reasons I'm selling my CRF and going back to the 520 is it great "Stealth" performance. :)

Oh, they'll step up. Once folks start getting busted or turned away from riding areas in Cali with the new law out there, the demand will be huge. Not just for KTM. Heck, most KTM owners can just put the stock bits back on and get by. Not sure about the SX exhaust, I guess.

My bet is that a system that is as quiet as the stock KTM sytem will offer VERY little to no performance gains outside of being a bit lighter. There just isn't the tunability there, like there is with the 2 stroke pipe, without the option to make them loud.

Omega, was that link for a dyno run? I couldn't get it to display.


I just saw a picture of a headpipe offered by KTM in the new Dirt Bike, is that an Akropovic? Where can they be purchased?

You can see the KTM systems that are available at Cycle Zone. Click on their 2003 hardparts catalog.

Hi All,

Thanks to all that took the time to post a response on my topic! I know the bike makes more power than most mortals could ever use. I was looking to reduce overall weight with a good cost to weight reduction ratio, fit & finish also come into play. Now the biggest challenge is to get the bike deal worked out.

Thanks Again All!

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