There's been a few recent posts regarding buying them and what to look for, and also things that are common issues, like MAF (mass airflow sensor) and Coilpacks failing.
Fitting a DV, is a piece of P! Remove old standard one, refit new recirc Forge 007 or Bailey DV30! That easy!
Before you ask, recirc's are the ones to run on these cars, as the engine management doesnt like the loss of boost, so gives the engine management light on the dash. A few have run atmos / hybrid dv's, on standard cars, but they seem to affect remapped ones even more.
You get a discount with forge motorsport if you order with them and mention you are a member on here, and they are 2nd to none in customer service.
There are a few other recommended sellers on here, too.
First few upgrades i'd recommend some eibach 15mm spacers for the rear wheels, around £80 delived from Badger5 motorsport. This helps control the twitchy rear of the car.
Forge DV
Strut Brace ordered through the authorised Seat dealers on here, so you get discount, about £50 delivered.
Just a few pointers for you.