Right or Wrong

[RUFIO]

I just got off the phone with a guy from a dealership, and he said that with a slip on pipe, twin air, no filter lid, that if i dont see any problems then i shoudlnt re-jet. I dont see problems so as of right now, I am not going to re-jet. Does anyone think differnt. And he said if i did re-jet, the differnce wouldnt be something i would notice

[stocktires]

I DO. With those mods you should deffinatley jet up, probably (big guess) around 3-7 sizes up (like example, from a 140 to a 150, would be 4 sizes up), talking about main jets here. The needle doesnt need to go up that much.
If you re-jet, your motor will run cooler making the top-end last longer, and you will see a small difference with re-jeting it.
Haveing a proper jetting set-up is the best hop-up there is.

[honda400exrider]

yeha i run lean with a clean k&n and a lid. DEF rejet

[Sportrax10]

yep rejet