Does anyone know if there is a difference in the aero-package and ACR downforce. Also is there any suspension difference in the aero-package over stock.

Yes I believe the downforce is 500 or 800lbs with the aero package and 1200-1500lbs with ACR Package and the suspension is the same as stock with aero package.

From SRT engineers The ACR makes significantly more downforce than either aero package. The aero package wings are based on the ACR form but they are twelve inches narrower (cross/car) and do not have the Gurney kick up at the trailing edge. The roadster aero package makes about the same downforce as a base coupe (roughly 170 lbs at 150 mph). The coupe aero package makes about 600 lbs of down force at 150 mph. The ACR makes 1000 lbs of DF at 150mph. 2003-2006 SRT-10: Front: 200 lb/in Rear: 500 lb/in Front Anti-roll Bar: 27mm Hollow Rear Anti-roll Bar: 27mm Hollow Michelin PS1 Tires 2008 SRT-10: Front: 210 lb/in Rear: 525 lb/in Front Anti-roll Bar: 27mm Hollow Front Anti-roll Bar: 27mm Solid Michelin PS2 Tires 2008 ACR: Front: 514 lb/in Rear: 1085 lb/in Front Anti-roll Bar: 27mm Solid Rear Anti-roll Bar: 27mm Solid Michelin PSC Tires Each of the Viper models are tuned specifically for: Tires Aerodynamics Weights Horsepower Wheel Alignment Differential Operation Etc. So to summarize, we would not recommend simply substituting 2008 coilovers on a 2006 model. In this specific case we would recommend at least the change of tires and rear anti-roll bar. Question: How much slower is the '08 ACR than a non acr '08 as far as top speed and 1/4 mile times? The ACR 0-60 times are identical to the 08 SRT-10. In the 1/4 mile, the ACR is about 0.1-0.2 seconds slower than the SRT-10. We just tested the top speed of the ACR at our Arizona Proving Grounds and reached a top speed of 177 mph. Of course the reason for the top speed reduction is the drag trade-off due to the downforce improvements. Although the wing, splitter, and diveplanes are extremely efficient (increase downforce at around a 7:1 ratio to drag penalty), the top speed will suffer. Don't worry too much, if they can catch back up to you on the straight, they'll have no chance of staying with you through the corner. Q1: What are the exact weights for the 2008 Coupe versus the 2008 Convertible. Is there still a weight differential of about 30 lbs as on the 2006 model? (With the convertible actually being lighter.) A1: Weight will vary from car to car but these are the official estimates 3,450 lbs. (1564.9 kg) Coupe 3,440 lbs. (1560.4 kg) Convertible 3,408 lbs. (1552 kg) ACR 3,366 lbs. (1533 kg) ACR Hard Core Package The non-ACR Coupe and Convertible went 202 mph, average in both directions to cancel out wind. The '08 Convertible went 197 with the top down. We had to go to TRC to go that fast. The Chelsea and Arizona proving grounds ovals are too small.