Turbo-Back Exhaust

[C.A.R.]

Right,

Decided that I'm going to treat the car to a new exhaust system as the current one is wank. I'll hang onto it in case it is needed for MOT time.

Now, I've probably asked already but -
- Best Internal Diameter (i/d)
- With no cat, will I want a silencer or just straight-thru?
- I definitely want a new back-box with a decent tip
- Will it be too loud? Bearing in mind baby will be here soon...

Any help much appreciated. What am I likely to pay from an independant? Doesn't have to be a stainless system, just do the job.