Note on removing the catalyser
There is a thriving market to entice you to remove the catalyser, also know as decat. With various promises of more power, more noise, more torque, less heat, less weight, or something else.
Removing the catalyser has a lot of cons however that you should consider first:
- The catalyser is there to make the bike cleaner. Reducing pollution is the only way to save our favorite pastime.
- Removing the catalyser is illegal in most places.
- This engine has been designed to have a catalyser installed. The engine management system will register the change, and will work outside of its normal range.
- At worst you may destroy your engine, and be denied warranty support from KTM.
Unless you have access to an engine engineer, a dyno, the ability to make your own ECU plus some very expensive hardware to measure pressure and temperature you probably should keep the catalyser.
The main reasons to replace the original exhaust can is to gain space, weight, change the sound, or simply for esthetic reasons. Power or torque gain will be marginal at best.
You will find below, in alphabetical order, some replacement you can install. Most (all?) are lighter than the original can, and some may have the ability to remove internal baffles to make more noise (with no minimal improvement on performance, if not negative effect).
Note also that a new exhaust may interfere with luggage options, or passenger legs. Or even melt the turn signals!
Akrapovič p/n 63505979000, about £875. Availble as an option from your KTM dealer.
This muffler can be modified to remove the baffle by drilling one hole and unscrewing a screw. This is a picture of the necessary hole. Please note that the dimension of 32mm measured back from the end of the exhaust to centre of the necessary access hole to be drilled is not 100% correct. See this post or this video with additional photos for exact measurements. A plug can be bought from Akrapovič to close the hole, and it is referenced by KTM (P/n 76505099050), about €3.
Arrow offers three different mufflers in alu and titanium, with removable db killer included. Optionally they also offer a mid pipe to replace the catalyser. From €500 for the slip-on.
Buyers beware: there are a couple of issues:
- Some models are not well designed for the 790, they are generic models that can be bolted on. This lead to disastrous results.
- Also note this comment on this post by Raymond Wilson: “I have GPR on my 1290 Super Adv […] the GPR mounting system with the external collar that wraps round the pipe is crap. I see they’ve used this method on the 790 Adventure exhaust and this alone would deter me from ever buying one”.
A slip on in various finishes. No advertised prices.
Two slip on, in various finishes. From €420 to to €490.
Remus also offers a specific 790 slip-on. €820. “Weight optimised”, not sure by how much. It’s quite nice in black…
SC project has multiple slip on available. €560 and up. Savings of 1.1Kgs.
Rade garage works with Sharon and offers a Rally style exhaust requiring the removal of the catalyser . €330. Not street legal. 3kgs lighter than original.
Wings. Coober couples it with an ECU upgrade. 2300g, 1.35kg lighter than the original exhaust. Includes removable DBKiller and spark arrester. €630 with the rear heat shield included. Heel heat shield is extra, €52. It is smaller than the original or the Akra.
Also Yoshimura has developed its own slip-on. Two different DB killers and spark arrester can be purchased separately. Saving are less than 1Kgs. $600. Just a heads up, the Yoshimura RS4 exhaust sits taller than the stock making the installation of some pannier racks impossible. Also with the added height the blinker get hit by heat from the exhaust gasses.