I think that your thinking is on the right track. The three cheapest performance exhausts are the Tecno Bullet, the Tecno Boss, and the Proma GP. They all have their pros and cons and people who like them or don't like them. I honestly don't think you'll go wrong with any of them, but if you want to read specific review of each, you'll have to do some searching (try here and on the gen forum).
On the jet, what size do you have now? If you have a 60 now, I'd buy 62, 64, 66, and 68. Start with the 68 and work your way down if you're rich. Basically, just buy a few sizes up from what you currently have. You can also check the spreadsheet and see what other people with similar setups are running.