Im finishing off the tubing from the intercooler to the carb on my car, and have a couple of questions:

Firstly theres quite a bit of silicone pipe rather than hard aluminum pipe, will this affect anything? Most of the cars I've seen use only small sections at bends.

Also, looking at the picture, the pipe steps up from 80mm to 90mm for maybe nearly a metre. Will the bigger diameter cause a noticable drop in pressure, and therefore cause a problem?

On the picture, the pipework is only roughly in place with no clamps

 

Larger diameter just means your blower won't have to work as hard to make boost.

That IS a lot of silicone. It will work, but over time, it may cause a ballooning effect and cause the hoses to come apart.