Okay folks need a little help I have a 2003 A4 1.8t quattro automatic. I've had it for a bit but i need more power I need advice

So my questions are

Which air intake carbonio or afe power or are their any short ram intakes out there? i would prefer the one that will provide more power.

Next which exhaust system would you guys recommend? again one that will provide the highest hp gains

Are there any headers for the A4?

And Diverter valve or BOV? I'm leaning towards DV right now but what do you guys think? and what brand is best?

And finally what software ?

What other performance upgrades can you think of, with out going to a turbo upgrade?

I"d appreciate any Input