had a recon turbo put on because my old one was making the siren noise. But now its really laggy and I get lots of black smoke.
One of your turbo pipes is off mate, When I had my hybrid put on it did this exact thing loads of black smoke and wouldn't boost properly, would also go into limp mode...
Get your turbo pipes looked at especially the small 90 degree one coming out of the turbo onto the metal intercooler pipe.
Darren