I would first install the front mount and tune the combo you have now. TA49s have been low 11s plenty of times. I think when tuned in, the TA49, front mount, Champion iron, etc. will surprise you. If you still crave more and would like to go quicker/faster later on down the road, a PT54 or TE45A (probably the limit of a "street" turbo) will do. Of course, only you can decide what is a "streetable" turbo. We all have different opinions on what we think is a good spooling turbo for the street . There are SO many turbo options for our cars now, choosing one can be mind boggling.
In my opinion, go with the smallest turbo you can since it is also a street driven car. You would probably do just fine with the TA49 or maybe a bit bigger like a TE62.