Is it a risk to put on aftermarket pipes without a tune?

I have the 2025 GT Storm and would like the exhaust note to be more noticeable so cars know when I'm around. Currently I don't believe there is an aftermarket exhaust available on the 2025 because of the dual O2 sensors, but when I contacted Competition Werkes they said they are working on making one available. I do worry, however that without a tune the cat delete and aftermarket pipes could end up damaging the engine, by making it run too lean for instance. I ride a lot, 12K miles a year and justified this purchase based on what seems to be great longevity of this bike, compared to my previous bike (a Ducati) that became a chronic problem after about 60k miles. What say you?

I have the same '25 GT and it has only one sensor. Did you confirm you have 2?

When I took the cat off, I had only one oxygen sensor and (now I am guessing) a connector for a second that seems closed off: imgur.com/a/M96ei9s from the factory. I don't know if USA bikes get a special firmware where the 2nd one (remember, still guessing) is disabled in the software?

PS: What you see on the pics seems like a connector with a hood. I did not unclip the zip tie yet to examine further. Also, a zip tie? Seriously? It probably would snap from all the UV here in Florida in a few years. Doesn't seem like forward engineering thinking..

Talking about dangers, I did notice a weird sound from the engine when running CW slip-on without baffles, it went away with baffles. Without the baffles I took only one single ride, and the sound was just too loud from the pipes, was I imagining that extra sound like woosh-woosh coming from the engine? Also, I noticed without the baffles on idle to slow speed, the torque has decreased, the throttle seemed liked needed extra roll to get a bike rolling without stalling from a complete stop. Once it just died on me at the traffic light, I was in 2nd gear stationary. Maybe the bike was still adjusting to the loss of cat.. Maybe a rider error? But, once I put baffles, I think I have 10+ hours with baffles and no *immediate* issues.

Good info A1A. I looked at my bike and found it the same as what you describe... an extra wire running down close to the cat but no direct connection to the cat. Perhaps ready for the new Euro standards but not fully implemented for U.S. models. So I guess mine is only 1 O2 sensor after all. But am I still correct that there is no tune available? Is doing a cat delete with no tune a risk to the motor?

Risk? Yes. Miniscule? Also yes. Nobody who's done it has reported any issues. I haven't seen anyone report seeing evidence of overly rich or lean running on their spark plugs, either.

Speak to your dealership is the best advice.

BrewinProf said:

I have the 2025 GT Storm and would like the exhaust note to be more noticeable so cars know when I'm around. Currently I don't believe there is an aftermarket exhaust available on the 2025 because of the dual O2 sensors, but when I contacted Competition Werkes they said they are working on making one available. I do worry, however that without a tune the cat delete and aftermarket pipes could end up damaging the engine, by making it run too lean for instance. I ride a lot, 12K miles a year and justified this purchase based on what seems to be great longevity of this bike, compared to my previous bike (a Ducati) that became a chronic problem after about 60k miles. What say you?

Click to expand...

As with any internal combustion engine, the fact of profoundly changing either the air inlet (KN type filter) or the outlet (decatalyzed or freer exhaust) involves reviewing the settings...especially since the factory settings are, at present, very very poor in order to comply with environmental rules which, if they are (perhaps) good for air quality, are very bad for internal combustion engines... In this moment we arrive at AFRs of 14.6 or even 15 or more and this is destructive for the engines...They heat up excessively because they do not have enough gasoline coming in (which contributes to the internal cooling of the engine). So, if you change your exhaust, you should at least install a map (free at that) from H. Penner or, better yet, put your bike on the bench for a specific adjustment to your configuration. If you don't do it, don't worry, you won't break your engine, but let's say it could work better (and don't forget to do the 12/15 minute reset before leaving!).

The ECU will not permit things to go out of control no matter what you do to any bolt on part. Might not be perfect in power or economy but no harm will be done

Thanks for all the input. I did call the service advisor at my dealer and besides warning that it is "possible" that adding an aftermarket exhaust could void my warranty he would recommend that the bike be tuned after removal of the catalytic converter and addition of an aftermarket slipon exhaust. Of course given that I live in CA, no dealer is legally able to modify the tuning, so getting it professionally tuned does not seem possible. After looking through the threads it doesn't appear that there is any DIY way to tune the new Storm ECUs, with Tune ECU for instance. Is that correct?

If I were you I would move to Texas or a less extremist state than California...