Gen1 1.6 non turbo performance modifications

Hi

I am from South Africa, have a 2012 Cruze 1.6LS sedan (J300), engine code F16D3 (non vvt).
The car has decent power on the top end ie. Freeway/highway driving, but due to being a big heavy sedan it is a bit lazy on take off or mid speed. It's completely stock and I was wondering if a decat(cat is on the exhaust manifold) and exhaust system with better flow might help with this issue. Too avoid the tin sound from knocking through the cat, I might need to get a custom exhaust manifold. Also, would dropping in a k&n filter make a difference?

Any suggestions or input?

Thanks