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When to increase main jet?



I've tried to do research, I pretty well understand how to re-jet, I'm not sure if I know when. On a 95 Sporty, if I go with drag pipes and big city thunder baffles and keep the stock air cleaner, will I automatically need to start with a larger main jet?

To my knowledge most manufactures 'jet' their vehicle for the 'leanest' conditions. High altitude States. They don't know where their vehicles are going to be sold when they are made, so they tune them RICH.

Since I live pretty much at sea level I do not worry about being lean. So, just vecause you change pipes, does not me you HAVE to change jetting.

Change your plugs and check them after a run. What are your plugs like? Do you have any backfiring? Do you know you fuel mileage before and after the pipes were changed?

Putting on drag pipes and keeping ham can will not do much other than make a lot of noise. if you increase the flow capacity of the exhaust but not intake you are limited to the CFM of the ham can, which is pretty poor. for another 90$ add in the SE a/c and vent the heads to air with just drag pipes, you will probably need to up the slow jet