Will GYT-R or PMB insert change jetting?

I am going to be getting a GYT-R or Pro Moto Billet exhaust silencer on my 03 wr450 and was wondering if I could jet it now and ride it or should I wait till I put the silencer in as it might change my jetting. I don't want to rejet it if the silencer will cause me to reopen the carb. I do have a zip ty screw so maybe that is all I will need to adjust. Any input would be greatly appreciated. :)

You live in Vail! You need to jet 155 main, JD red needle #3 for summer and 160 main and JD red needle #4 for cooler conditions in early fall or late spring. Insert wont hurt much at that altitude. :)

I don't live at the same altitude or have the same bike but I do have the gyt-r insert in my bike with the air box snorkle out and I have stock carb settings. My bike runs very strong however with it getting warmer out it may be running too rich. I think I can compensate with the Fuel screw but if not I will go with a the next leaner main jet. Get familiar and intimate with your carb, your bike will love you for it! :)

I have a PMB and had the GYRT insert and had to rejet to use these. It just ran too rich with the smaller outlet. I dropped the needle one clip and went down one size on the main.

The main reason I finally changed to the FMF Q was that I thought the exhaust seemed extremely hot compared to running the open exhaust.

Just a thought for you. The moto billet unit made the bike run stronger on top compared to the GYT tip. Also my GYT tip mounting bolt hole had to be heli coiled to keep the bolt in. Didnt do anything but twist the air screw here at 3600 ft and it runs fine.

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