If so what are the benefits to this? l understand that the gear ratios will be less but aside from that l do not know.
Its a 2007 by the way.

It all depend on the money u r willing to spend off hand l can tell u that about 5 different 6 speed manual transmission can be fitted to about 99% of the vehicles in the road & about 8 will be available withing 2 years both automatic & manual so if u choose either all u need is to contact the manufacturer of any transmission & order it. Just remember that if ur vehicles manufacturer does not offer a 6 speed transmission for ur particular vehicle that will mean ur factory warranty will be void. There is also more to just putting the transmission there has to be programing of various components in ur computer, is a nice project so GOOD LUCK....

With enough $$$, anything is possible.

it would cost far more than it is worth to do.

youd be better off selling the car and buying a 6 speed. The tC 5speed is fine anyways though so im not really sure why youd be considering this.

it would be possible like others said and it would help greatly on highways. the only thing you would really have trouble with is the computer. The real benefit would be when you cruise around 65-70mph on the highway your rpms would be lower so you should get better gas mileage. Since the rpms are at like 3500 it would drop them to probably 2500-3000. l just found this site and ZP l is working on a 6-spd tranny for the tc.
http://turbokits.com/tC_turbo_kits.html