First off, aftermarket pipes fit with stock mufflers right? (RCR mid range pipe in perticular)

What jet sizes do you guys use with your pipes and K&N filters? I have RCR's airbox mod as well so is 260 a good main jet to run?

Also how do spring weights work? Would a heavier primary spring be for top end and a lighter one be for low end or is it the other way around?

 

There are many other factors involved in jetting than just choosing a pipe like elevation, weather, and additional mods.

I'm assuning you are reffering to the OEM 34mm carb?

In your second question and you asking about springs or flyweights?

 

yes, with a stock carb at realitively close to sea level.


Also i mean the spring's weight. As in rcr sells an orange one and a green one for either low or top end, but what is the difference, as in which one would be considered "heavier" and it does this? and "lighter" because it does this?

 

The RCR pipe uses a clamp on type of silencer w/o a spark arrestor, but modifications can be made to use the stock ( heavy ) silencer / spark arrestor.
Start with a 270 Main jet and work down from there, don't jump to the lean side at first, work your way down and check the plug as you go.