What did GM change between the 97 and 2000 L67'*? The question I ask is because our SSEi seems to have better throttle response right off of a dead stop and even on slow acceleration it will rev to around 2,5000 RPM. The 97 riviera on the other hand takes more throttle to get going (not as much throttle response) On the same acceleration level as teh bonny though, it'll shift at around 1,700 RPM. The gera ratios must be the same because they both are at the same RPM at every speed if you're cruising and not accelerating. WHat I don't get is why they're so different. Think the PCM programming is just that different? Merging onto the highway is much better in the riv though, that car flies once it'* moving. I"ve had it chirp the tires on a 3-1 downshift at 30 MPH. In fact, the 0-60 time is actually 6.9 seconds just with the mods in my sig. So why is there such a difference where the bonny has more throttle response, but the riviera seems to have better acceration?

Could be the tranny...
most likly buick power as apossed to pontiac power..

I would think that the buick has a different gearing. Is the weight any different?

They both have the same gear ratio as determined by RPO codes and they are the same weight within 100 or so pounds, they're both G-Body cars.

Maybe you need to clean your TB? Sensors could be off, etc. Fuel system treatment, blah blah blah...

A more restrictive exhaust?

btw Custom? whats your plans for the rims once you get new ones?

Everything is the same, including the trans. The exhaust could be the difference.

I'd bet the PCM is tuned a little different. Does the Riv. have a performance button? Different Traction controll systems, Magna-stear?

My father has a '97 Park Avenue Ultra. I find the driving characteristics between the PA and my SSEi to be remarkably different.
The two cars are only one model year apart, with the same L67 engine, the same size tires, and were built on the same assembly line in Flint, Mi.
Dad is 78 and has had a number of health issues lately. I frequently drive the 12 miles to his house, switch to the Buick, and take him to the doctor. Then I switch cars again and go home. This back-to-back driving of the two cars has given me perspectrive. It is quite surprising how two cars so similar can be so different in some ways.

The PA runs a little higher RPM'* than the SSEi at equal road speeds, indicating taller gearing in the Pontiac, yet the Bonneville is noticeably quicker and more responsive throughout the RPM range at all speeds.. Several things can be the cause of this, I think:
With the exception of Mobil 1 oil, the PA is unmodified, the SSEi has the few minor mods listed in my signature below.
The PA might be carrying a little more weight- don't know for sure, but it feels like it.
The PA has only 18000 miles on it- while my SSEi has 134000 miles and must be a little "looser" engine, exhaust,and other-wise.
Who knows? No two cars are alike.

The PA gets better gas mileage than the SSEi, even when I drive it. Maybe this is from newer and fresher sensors, etc.?

The most dramatic difference between the two cars is the "driving feel". While the PA rides much smoother and soaks up bumps much better, the SSEi handles much more responsively and to me is a much better driving car. The PA has the electronic suspension and the SSEi does not.
I have owned many Pontiacs and a few Buicks over the last 30 years and describe the driving impressions of these two cars thusly:
The SSEi drives like a Pontiac: A little firmer and less plush than the Buick, but better handling and more responsive.
The PA Ultra drives like a Buick: A smoother, quieter ride than the SSEi but less responsive- the steering (both have magnasteer) is numb by comparison, and the Buick is not anywhere near as mush fun to drive on the twisty roads around here.

To each his own, I guess. My Dad greatly prefers his smoother and plusher Buick, and I prefer my sportier Pontiac.
It'* pretty amazing how GM could make the two cars so different. Each one follows it'* brand name tradition while sharing so many components.

im pretty certain that the 97-98 L67 Series 2 3800 has a less restrictive TB.
There also may be a difference in the parasitic loss with the pulleys...fancy electronic stuff. Also probably the PCM'* are tuned different.