What's the best/easiest/cheapest way to boost the power of my 2007 America?

Can it be done keeping the stock pipes?

I understand that some people are thrilled to tinker with their motorbikes. I am not one of them. I'd rather work for the money that costs having it done.

I have 3200 miles on my America, and it's getting smoother but it has a sluggish spot around 70 mph. Unlike the Bonnie this is a bike that doesn't jump forward when you accelerate. It takes its time. If I wanted a rocket I would not have bought it but I little more oomph would be welcome, having enjoyed the brutalities of a Norton Commando in my misspent youth.

I see there is a mod to bring the cc's to 904. That's not even adding the power of half a moped, to the stock 865 cc. And it costs almost two grand to have it done if I recall correctly.

I had the AI removed. What else would give it a noticeable boost?

I read the instruction for putting the freak filter on. Unbelievable, you have to disassemble half the bike.

I'd pay $500 to the dealer for a "tune up" to give it a few more HP, but I don't even know if it is possible or worth it at all.

Comments welcome and... thanks.