He needed a massive intercooler as he was running it with a larger hybrid turbo, he said it wouldn't actually improve your performance noticeably on a standard or even remapped car, but it was one of the bottlenecks if you want to take your car quite a bit over the 200bhp mark..
He did it all himself, and intercooler and fitting and what not cost him around £600, and thats not including his own labour
Battery also needs to be relocated to the boot for it too! But price up new intercooler, plus fitting, and see what the difference is. Would you be comfortable doing a big job like that yourself?
Also, if you did go down this root you would have more turbo lag, and the turbo needs to suck more air to fill the longer pipes and bigger intercooler before the air gets to your engine. I will only be going down this route if my turbo pops, instead of replacing it as standard I will try and source a larger hybrid Garrett model.
The smoke and responsiveness was the exact same symptoms as mine with the cracked intercooler-throttlebody pipe, as the engine isn't getting all the air that the air flow meter reads it as getting. Therefore it runs rich, causing incomplete combustion and smoke. Just keep an eye on your oil level for now but I can't imagine its losing much from here, but you should look into getting it sorted soon, I can't imagine the extra soot is good for the cat and exhaust system.