Tuned cars are sweet, but they usually have minimal or no warranties, mediocre reliability, and tiny, underfunded customer service departments. That's not sweet. Luckily, a number of companies own tuners, and churn out their own tuned cars, which are some of the coolest whips on the road right now, and come with at lease passable reliability, good warranties, and the same customer service as the big marques that own them.
Basically, it's the best of all worlds, and if you have some spare cash under the mattress, you should pay extra attention to The Complex Guide to In-House Tuners.