There are ALWAYS going to be better aftermarket options on a Harley, simply because EPA has restricted performance on these scooters pretty severely. Will doing a Stage 2 be an improvement- absolutely. The difference is that anyone who's trying to wring out every last ounce of performance for their hard earned dollar knows that Screaming Eagle isn't going to get you there. That being said, if you're new to riding or don't know what you're missing, I think you'll be very happy and content with a SE Stage 2 kit from the dealer.
Lastly, it has already been mentioned, but you're going to have to retain SE parts if you want your warranty to stay intact. If you move to aftermarket tuners/cams etc. there is always a chance that you are going to void your warranty- even IF your dealer says they will take care of you no matter what, a dealer 200 miles down the road that you need to call on in a pinch will say your warranty is void.
If you're going to stay local and your dealer is going to service you no matter what, I'd get it in writing and start looking at some aftermarket companies for your parts (fuelmoto.com being your first stop since they have parts and dyno sheets to show you performance). If you plan to travel and hate the idea of putting your 2 year manufacture warranty at risk, stick with SE parts and know that though you're leaving "SOME" performance on the table, you're still making really solid gains over your bike as it sits.
Best of luck, congrats on the scoot and let us know what you decide!!!
Recently purchased a 19 RGS and looking to improve the performance. The HD dealership is suggesting Rinehardts exhaust, heavy breather, screamin eagle tuner, and their Torque cam kit. I'm new to riding a Harley and have heard that there are always better options than what screamin eagle offers, not saying they're bad. Also I am concerned if some of these options will void out any warranty.