Use mine all the time when traveling, 70 + mph. But I don't think the car likes it, like it's being punished. Drop it down a gear or two & she smiles & comes alive.
6th Gear in a Viper is a free gift from Chrysler to remind you why you purchased a Viper in the first place.
When you shift into 6th gear at any legal speeds your Viper turns into a Neon. No torque, hp or performance.(you do, however get better fuel economy)
I have a C6Z and Gen IV Viper. I always use 6th in both vehicles while on the highway at speeds over 70. If you think 6th is too tall - have you ever seen when it force shifts from 1st to 4th?? You can safely put both cars in 6th at 50-60 mph with no issue.That's about what I was doing too but anything below 75-80 seems a little slow for 6th. I'm coming from a Corvette C6 and would use 6th gear every time I got on the highway.
That's why I changed to 3.55's on my 09 coupe. Now 6th is usable from 65mph+, goes up hills easily and gets 20mpg +- depending on how much alcohol is in the gas. Running stock rubber.
There is another option to swapping rear gear ratios. I just swapped 5th and 6th gears in the trans of my 09 ACR. Went to .80 5th and .63 6th. Car really likes these gears with the 3.07 OE rear gear ratio.
Dan
I use 6th all the time. Cuts down on heat, increases engine longevity and mileage.
I have both .80 5th and .63 6th PLUS 3.55 out back. With 18" tires this is the perfect gearing. Redline in 6th is 200 mph which means the theoretical top speed in the mid to high 180 mph range is right at the power peak on a dyno chart in 6th gear. And 6th is now very nice on the freeway, but I still bever get into 5th driving around town.There is another option to swapping rear gear ratios. I just swapped 5th and 6th gears in the trans of my 09 ACR. Went to .80 5th and .63 6th. Car really likes these gears with the 3.07 OE rear gear ratio.
FYI, the 2010 Vipers will have .80 5th but retain the .50 6th. 6th is for fuel economy as stated above.