Can't go pass 30mph!

Hi I had taken off all parts necessary to change all the gaskets for a slight rebuild of the turbo, gaskets and such. After reinstalling all components, It had a steady idle at around 800rpm and oil pressure was good as well as water temp and all. However, while doing a test run, I noticed that my boost gauge did not want to go past 0; so I guess it wasn't building pressure; also the car didnt want to go past approx. 30 mph. Also theres slight smoke seems to be coming from where the turbo exhaust flange and down pipe meet. Any Help and/or suggestions will all be greatly appreciated. Thanks