To speak on behalf of what I sell... The GT28 conversion kit like I had on my 996TT is pretty awesome. It does use external wastegates which generate a ton more power and torque then a K16/16 or a K24/18G. Especially with the supporting mods that Bad107 has bought. The hard parts kit is $3000. You can see the below options and recommended parts on that link below. In the OP case, he would only need to get the Turbos/wastegates in addition so he would spend about $5500. This is a MUCH better option then the internal gate Tial Alpha. http://www.vividracing.com/catalog/v...5-p-50924.html



http://www.youtube.com/watch?v=HIpqG97j9J0

As far as the other Turbo Packages I have, the price is for the conversion, though I do stock already modified cores here. Right now we have both the K24/18G and K16/16G instock with 1.0bar actuators. I ship you these, you ship me your stock turbos back. All these packages with recommended parts can be seen here - http://www.vividracing.com/catalog/t...8&filter_id=31

We did a K16/16G car with all the "a la carte" options seen on the bottom of the package here. Much of the same mods as the OP except this was stock injectors and no intercooler pipe kit. This was also a Tiptronic and on 91 octane pump gas on our Mustang AWD Dyno it put down 493hp and 559ft/lbs of torque. Do the drivetrain loss of 20-25% math. Pretty damn good You can see the full build here - http://www.vividracing.com/forums/ga...?i=13258&c=495

http://www.youtube.com/watch?v=E1F7BKxl4Fw
http://www.youtube.com/watch?v=cNp4SF0-2XM