An '07 Taurus has a Vulcan engine. There is really little you can do that will make much difference shy of oversize valve, a cam, or maybe a turbocharger or supercharger. The Vulcan has a hard time breathing, its an antiquated and actually obsolete design that originated in the mid-eighties. It is overall a durable and cheap design, but performance is not its strong suit. Gutting the cats would probably make it less powerful, since the factory cam is designed to factor in the presence of cats, most people who gut cats have a decrease in economy and torque. A tuner can help offset, but the cam is designed to be used with emissions components to maximize performance.
If you really want to see what you can do, either be prepared to spend real money, (not gutting cats), or go get a faster car. There are a few cheap mods you can do with the intake, and you can go with freer flowing mufflers, but even those are more for sound, and don't translate to much improved performance on their own. A straight through type muffler and slightly increased pipe size will help give a little extra power, 2.25" is a good size, larger than that can sometime cause a decrease in torque and throttle response due to a an increase in the total mass of air in the exhaust system, it takes more energy to move a larger mass.
SHOsource sells a few performance enhancing parts for Vucans. At the end of the day though, the Vulcan is not a performance engine by nature, it has only two valves per cylinder, and it does not flow well unless the heads are smoothed out and enlarged slightly through a process known as porting. You might be able to get larger valves, and performance cams increase the lift and duration which increases flow, and as a result, performance. Major mods like this often require tuning changes too, to change the timing and fuel mixture to match the changes to the engine.
If you convert to turbocharged (or supercharged), the boost helps overcome the restrictive heads (I would still port it, but the stock cam is usually fine.), but for best results you either have to limit boost, or take steps to lower compression. This approach is one of the best bangs for the buck, but is still expensive.
Not to discourage you, I always thinks its cool when someone modifies a Taurus, especially as its not a popular modders car. But I also tend to look at things realistically, and the truth is, the Taurus is not a modders car for a reason, squeezing performance out of a small pushrod V6 is difficult, especially when performance parts support is not that great.
The Magnaflow y-pipe does nothing for performance, in fact it is inferior to the OEM
one from a performance standpoint.