Carb jets for new exhaust

New to the forum, trying to figure how to post etc. Thanks for your patience.

I have a carb jet question relating to exhaust changes.
I put a Santee 2 into 1 header on my '02 FXDL.
Can I use the stock unmodified muffler on this header or would it be too much back pressure since it was for a dual muffler exhaust?

The stock carb jets are 45/190. I don't know what's in there now but the idle mixture plug is absent and the setting is 2 1/4 turns out. To accommodate this exhaust set up what jet/mixture settings are recommended?

I have some trouble shooting to do for a carb cough/fart on acceleration and occasional backfiring on deceleration. I will check for intake leaks and try mixture screw adjustments. I have read hours of posts on the subject on this forum, thanks for all the great info and advice, but I need some direction on the required muffler/carb jet sizes for a 2 into 1 exhaust.

Do I need to have a dealer dyno test it?

Thanks