While Porsche's designers can jokingly be accused of being some of the laziest in the industry due to the incremental changes to the 911's iconic design, no such charge can be leveled against the engineers and product planning folks. That's because it seems like each week arrives with news of a new variation of the marque's iconic rear-engined sports car . So, for this week, we've brought you images of what we think is the new 911 GTS Cabriolet, undergoing testing in a thawing winter wonderland.Now, what is it that gives this 911 away, compared to standard convertible? Well, the big thing is the new offset, center-mounted exhausts. Borrowing a page from the last Volkswagen R32 , these exhaust tips are unlike anything we've seen from Porsche . Only the GT3 wears center pipes, and unlike these spy photos , the twin pipes on the track-minded 911 are stacked neatly alongside each other. The other change spotted by our spies is the set of active-aerodynamic flaps in the front bumper, which can automatically channel air toward the brakes for increased cooling, or close off to reduce drag, as needed.Those exhausts are a pretty big design detail, and so far as we can tell is the only differentiator between the other 911s in this car's posse. Our spies speculate that this could be a 911 Speedster , but point out that both the canvas roof and windshield remain unchanged - the rumored Speedster model would almost certainly feature a different roof assembly along with a steeply raked windshield.Further confusing things in this case are the presence of 911 Turbo-style fender vents. They can't clearly be made out on the 911 above, but are quite easy to spot on the 911s in the background. Couple that with the two pairs of slats in the rear fascia, which are present on these cars as well as in previous spy shots , and it becomes very, very difficult to figure out what Porsche is up to. GTS, perhaps?Whatever this car is, we'll be keeping an eye out for more information on it. Until then, what do you think Porsche has planned? Let us know in Comments.