Can I get an air intake or the roadster that will increase hp?

 

The short answer is, No. The intake is already optimized for the operation limit of your car.
If you get the ECU upgraded then I would pick up a 320 c-class intake, I think it breathes and has larger air filters, so it is a little better than the XF's intake system. And don't waste your money on that Ebay intake crap. That let's hot air into the engine, it's not gonna make more power, just a loud noise of the intake.

 

the airbox from a 500 series car, like the e500 or sl500 is significantly larger than ours and a bolt on mod. probably 3 whp in there. but get the speedinovations ecu, by far the best bang for you buck. $450 dollars will net you 20 whp.