Hey Ryan,
I've been trying to email you but keep getting undeliverable responses. Hopefully you can answer my question so I can move forward with purchasing a pair of 4" Big Louie slip-ons for my 2011 FLTRU (stock headers). I plan on adding a stage 1 Arlen Ness Big Sucker as well. Am I right to assume the 2.5" baffles are the best size for this setup?
Also, I would like to know if the 3518 tips would fit the 4" slip-ons?

Thanks and I hope to hear from you soon!

 

We recommend the 2.50" or the 3.00". We have been pushing the 3.00" because most customers like them and it's one of the most aggressive slip-ons you can use with stock headers. The tips for the Big Louie will all be 40xx. Check out the packages we have available that include certain tip options. They are listed at the bottom of this page http://www.rushracingproducts.com/big%20louie.html