121kw vs 117kw, 7.2 sec vs 7.5 sec, I think its all trivial differences personally, I doubt you could tell the difference in the driving.
 
Years ago on a club dyno night, a gen 2 NA with intake (cold air), custom extractors,  exhaust (plus some other bits I cant recall) was similar power to a stock gen 3 NA.  We were surprised as the gen2 had lots of goodies added and was basically the same as the gen3.
 
I know one mechanic used to advance the timing ((and then you could only use 98 octane fuel) for a bit of an easy gain.
 
But if you want a significant increase in power, just get a 3sgte, you will definitely notice the difference.  
 
If you are going to spend a grand or 2 chasing a few kws, you will probably be better off spending it on getting the suspension sorted to your liking.  Thats what I would do.
 
Cheers