I have a 2021 KLX 300 with the following Mods Delkevic Slip On 14” with the spark arrestor baffle installed. I removed the Secondary Throttle Plate, and that gold spring next to the throttle cable on the outside of throttle body, removed O2 sensor have the O2 eliminator installed. I went back to the stock air box no mods on the air box now. No tuner! No check engine light on. The header is glowing orange at 6000 RPM in 5th and 6th gear. Pulled the plug it shows signs of running lean. Went to a cooler plug no change header is still glowing orange. Covered half of the snorkel with tape, seems to be a little better. Removing the STP is great instant low-end torque. I do not want to buy a tuner. It looks hard to install and program. I do not want to ride off road with a hot header or on road for that matter. The manufacturer of the Dekevic and the O2 eliminator say the header should not glow at all with the mods I have on the bike.

 

Pipes will glow if you let the bike sit and idle, but moving, the air should cool it enough to not glow, and especially not glow orange. Cooler plug won't do a thing for that situation. I'm betting it is lean and you will need to do the tune