156 mph sounds about right. We currently own a 1996 Impala SS. Went 157 mph on I-5 late one week day evening. If you decide to do this, make absolutely sure your tires are new, in perfect condition, and properly inflated. If one comes apart on you at that speed, you will not survive.

 

The 2006 had the highest limiter at 160mph while the 2007-2009 was limited to 148. It will do about 155 before i wont go no more.

 

i've had 2 04 imp ss, the first one had no work and it hit at 112 the second one i tried to hit it one day and she kept going till i let off around 130. the road was ideal for me to be pushing it and stock the 04 imp came with W rated tires (168 mph)