need help please with my mk1 clio maxim s engine.

[zzAfRozz]

hello. Bought a 1997 mk1 clio maxim s around 3 months ago (the car had been lying for years) and have been working on it to try get it to perform at its best. i have done all the major work to it and have successfully put it through an M.O.T. since driving it on the roads i have noticed it only starts to properly accelerate at around 4 or 5 k rpm (there is quite a noticeable difference.) is this normal ? i have noticed from comparing my engine bay to pictures of others that one of the pipes from the air box that goes to the exhaust manifold is missing , will this cause any noticeable differences ? is there anything else that i have missed that may be the cause ? Again comparing it to other pictures their are things that seem to be missing. also any tips to make it faster ? help appreciated...Thank you