I know (or at least I'm hoping) I'm going to open a can of worms with the following question. Put yourself in my shoes for a moment and you now own the stock 09 harvest orange CUSE4 to your left. You have somewhere between $500 to $1000 to spend on enhancements before the ol' wife tosses you out on your keester, and that's all you're going to have for a couple of years. What changes in the stock would you do first, and why, and what do you think it would cost?

Can't wait to hear what you have to say -- Bikin' Bob
I've lived in those shoes for 2 years now, and with the purchase of the SERG, I'll wear them for another few years.
There's actually two legitimate lines of thought here. It all starts with "just letting her breathe a little better". It could be compared to "the leg bone's connecting to the hip bone". Just a better air breather, some slip ons or a complete exhaust, and a slight modification to the ECM to richen her up. The problem with only modifying the leg bone while maintaining a stock hip bone, is the stock hip bone restricts the potential performance of the leg bone. Wifes will generally be ok with a modified hip bone, but, whenever you start modifying the leg bone, even a good woman will get frustrated with your decisions. It's a catch 22. You and I both know you have to modify the leg bone. Do you want your HD to be right or your marriage? If you're like me, I prefer both. $500-$1,000 budget restrictions are unrealistic as we both know, but wives don't know that, at first. Knowledge is power. At some point the wife will figure out the budget is blown. Just how far can you take it before she balks?
The second line of thought is the approach I've decided to take with the second bike, at least for now. No new slip ons. No exhaust change. No ECM changes. It breathes like a man with a sinus infection, but, it's a HD. I have two. One breathes good, this one doesnt.
Hope this helps.