I know that you said the Cobra was stock, if you do not have an aftermarket mid-pipe such as a Bassani or MagnaFlow and maybe for sound than performance a nice cat-back muffler system. Get some 4.10 gears installed because the car is really under geared with the 3.27's. Maybe put a nice cold air setup and then get some under drive pulleys installed. Not much to do to the engine performance-wise unless you want to pay mucho dinero for long tube headers and/or any type of forced or chemical induction, ie; nitrous. These Cobra powerplants are plenty stout but the Hypereutetic pistons, are great for naturally aspirated engines because they keep oil burning down to a minimum with the low friction rings but not for stuff like I just mentioned. Oh, and the rods may not hold up as well. If you decide to do it anyways, you might want to either rebuild the engine outright or put money in the bank when the time will come that the engine starts to fail.