You are heading into a world of grief. A modified car is never as reliable as a standard one. It will cost heaps more to insure since modifiers are usually boy racers and rated accordingly. When you sell it the market is tiny and the price similar, dealers will not want it.
You admit you are strapped for cash, this is the last thing you should be doing.
Save up until you can afford the car you really want and enjoy the Ceed for what it is in the meantime.