I am about to replace the OEM 19 Bridgestones on my coupe and found a good deal for the Falken fk452 tires. If I leave the front tires unchanged will this cause issues since I will have two different brands of tires?

 

As long as you keep same brand on one axle you are fine.

If you start mixing them up you can find your self going sideways for no operant reason.

 

its hard to say if its going to be a problem or not, but it can be. There are mixed results, with some people not having a problem, and some people who's VDC started going crazy. If you are going to try it, make sure the new tires have similar performance characteristics to the stock tires in terms of grip etc.