I'm having difficulty visualizing your entire system from partial pictures. Before you start buying stuff you need to determine what type of exhaust system you have. Is it really a waterlift or is it a standpipe? The two achieve the same goal but are very different and the components are not interchangeable without a full system redesign. As far as we know right now you may even have a straight pipe system with a silencer, also different from the other two.
If better pictures are not possible, perhaps a detailed drawing?
Please study the drawings attached to
this post and report back if either of them reflect your system. Look particularly at relative elevations, water injection points and hose gradients to the transom (the standpipe runs downhill, the waterlift usually has a hump).
edit: you my find
this YouTube video helpful. It's of the same boat as yours and follows good marine exhaust principles pretty well. Do not be tempted to use galvanized pipe however.