i disagree with some of the advise, i personally driving a bolt on turbo on my SGTI and i dont think is waste of monies as it give me pleasure and knowledge on the engine capability more than anyone who just transplant engine into their car......... they dont even have knowledge on what thay are modifing........ what they know is only power not knowledge.
bolt on turbo is not an easy work to do, you have to think : -
1. what turbo to suit your engine?
2. What manifold you use?
3.what cc injector you put?
4. Do you have to change ECU, change chip or put AFC ?
5. Do you have to change piston....etc?
if you have answer for the above and the amount of monies spend is within your budget, you may give it a try? my car is running at 1.1 bar max and it doesnt bring me any trouble?