Is there anything to be gained through fuel tuning on an s5 with stock ports?

 

yes, on a non turbo you can pick up some horsepower by leaning out the mixture

 

^Which is exactly why there is a market for SAFC's.

As a former Navy brat, I lived in Oak Harbor for a while back in the 1970's. Talk about living in a place with spectacular views, but not much else to do. I'm sure that latter issue has improved since.

 

do you need an aftermarket ecu or can it be done with the injectors alone?

 

a stage 2 rtek can do the job, but for the price you could almost go megasquirt. an SAFC is about the cheapest way to get that job done. The only place its stupid rich is on top end(pretty much above 6k at WOT). On stock fueling with a wideband my N/A would read in the high 10's and 11's on top end. Max horsepower is only going to slightly go up, but the power curve will extend out to almost redline but leaning out the top a bit.

 

does the rtek come with presets or does someone need to program it?

 

An Rtek 2.x starts with all stock settings until you modify it. There are different injector presets you can choose from as well, which will automatically update the fuel map.

But an Rtek or standalone will have a lot of features you may not really make use of with your average NA engine. If all you want to do is pull a little top-end fuel, an SAFC and wideband can get the job done for the least $$. If you want to adjust timing, adjust injector staging, use larger injectors, datalog, etc... go Rtek or standalone.