I ran my 4" Jackpots with the stock header for about 450 miles. It was ok, but the best performance, feel, and sounds thing to do is get the 2-1-2 header and make it all work wonderfully.
I'm very happy with mine; seen below.
Thanks for the pic!!!
Just ordered the 4" slash up Jackpot Tuned mufflers and the ceramic exhaust headers from Fuel Moto. Due to the 6 week turnaround on the ceramic coating, they are going to ship the exhaust with a map for my set up next week so I can install it. When they ship the header they will email me an updated map and they are not going to charge me again for the shipping. Now that is service.