What's the HP ceiling on an S4 NA ECU?
 

I'm in the same bind a lot or S4 NA owners are in: I want to hop the 7 up a little but I'm on a tight budget. I'm open to doing small things but at the moment, a standalone or fuel computer like a SAFC is out of the question. So when you can't touch the engine management, what can you do before you're wasting your time? Some of the small things Im thinking about are 5/6 port sleeves, S5 UIM, EGR delete, etc. I have an air intake and catback already. Will any of that help, or am I limited to what the ECU can do?

you won't reach the limit of its capability, so don't worry about it.

the only real problem with the S4 NA ecu, is that it doesn't seem to drive the injectors very hard, stock AFR's can be as lean as 12.8.

the good news is that if you need more fuel, you can always drop in some T2 secondaries, or bump fuel pressure

I thought the n/a’s always ran rich? Or is that just the smell i get from mine lol

smell and actually being rich are different. S4 NA runs 14.4:1 at wot up to about 4500rpm, then it dips to 12.2, leans out to 12.8 at about 6k and then goes rich over 6500.

the S5 NA runs the same 14's up to 4500, then it does the same dip to about 12.2 at 4500, but after that it gradually richens up until its about 10:1 at 7k.

the S5 had big feeling gains when you go from 10:1 to 12.5:1, the S4 is already leaner than that, so if anything it wants more fuel