We have a used Milltek system at our place that we're storing for a customer, priced at about £650 and only covered about 3000 miles, if you're interested let me know and I'll put you in contact with him...
The 350z system is Cats - Y Pipe - Mid Pipe - Rear Slencer...
If your exhaust has failed where the mid pipe meets the rear box, then all you need to replace is the Mid and Rear as most members opt for...
The £395.00 is for the Y pipe back system, which includes the Mid Pipe and Rear Silencer, if you wanted to make it a Cat back system then you'd need to add the Y pipe which is an additional £199...
Dal, we have a few options you can choose from, Cobra Sport Exhaust and Scorpion are two examples that are good value and a good upgrade for the OEM system...
Drop us a call or PM If you need more info...