I recently bought a C3 1.1 (TU1A) 2009 with the expectation (my mistake) it was as nippy as the other cars I owned before (900cc spark, 2x C1 1.0 3cyl 12v). This one has more a "joie de vivre" so to say...
The engine runs just fine, but lacks power so to say.. (is sluggish to 4000RPM and then wakes up a bit)
I've calculated the weight power and I need a minimum 20BHP more then factory (59BHP) to get the same weight/power of a C1 (68BHP).
Does anyone have experience of tuning/upgrading/modifying this engine? Or know of someone that has? It has to be done within the stringent regulations/legislation/emission in the Netherlands (where I live), so slapping on ITB's and replacing the cat is a nono.. And I bought the 1.1 for a reason, fuel economy

They say that just "chip tune" the ECU will give 13BHP more, should changing the air-filter for a more sporty one give me that 7+BHP more?
BR
Remi