hi everyone
i have a 99 SSEi with what appears to be original exhaust
its going to have to be changed (ahh snow and salt in the great white north)
its welded so its going to be a cat back job...
i looked at borla catalogue... didnt see anything for mine...

ive used walker in the past on other vehicles... and i am thinking of the DYNOMAX this time...
im looking for increased performance... a bit of rumble wouldnt hurt but i DONT want that annoying rice sound.

not sure about resonators as i didnt look that close....
but if they are there im probably going to have to keep them as we have emissions test here in Ontario.

if you need more info let me know and ill post.

First of all, can you put '99 SSEi' in your signature by editing your profile? That way people know what you have each time you reply or post, rather than having to go back and read your original post in the topic each time.

Your exhaust is 2.5" Mandrel-bent stainless steel. Your cat and muffler may rust out, but I doubt your pipe will.

There isn't any performance to be gained by changing the muffler. Some of the quickest L67'* on this Forum still run stock mufflers, and typically do until they hit the 13-second range on the 1/4 mile. So change that for sound alone, not for a kick in the pants.

Nobody makes a cat-back for our cars, but again, as you can see, it'* not necessary considering the performance and quality we have from the factory. A hi-Flow catalytic converter would do you well. You won't gain much on a basically stock car, but it sets you up nicely for future flow-improving power-adding mods.

The vast majority of Bonnevilles here run either Magnaflow or Flowmaster. There'* one or two running Dynomax, 3 running Hooker.

the factory isnt bad for n/a motors but if ou want some power get a downpipe thats one of the biggest restrictions because of internal diamter of that section of exaust is really restrictive despite the overall diamter seeming to match everything else. So if i were you id invest in a downpipe it will be worth the little bit of money

91PA, going to a larger downpipe on a mostly-stock L67 results in an immediate loss of low-end torque.

Downpipes are something that happens MUCH later in the modding game. Typically with either a cam or rockers, and PEM'* or Headers.

DP is bad advice on a nearly stock or bone-stock L67.

a 2.5 inch DP looses power ok

well ill quote ZZ Performance

"Stock downpipes are double-walled tubing with an inside diameter of just over two inches. Following the restrictive downpipe section, the stock unit subjects the exhaust gases to the choking effects of the catalytic converter. After the cat, it flattens out into a section dubbed the infamous "U-Bend," which is a section of pipe crushed into a "U" shape by GM in order to fit a rear O2 sensor. This section has less volume than the same length of 2" pipe, and approaches the volume of a 1.75" pipe with the rear O2 sensor in place! Our downpipe eliminates all of the aforementioned problems! Gains of over 15HP have been seen, along with a substantial drop in knock. Most users can drop a pulley size and/or eliminate 5-7 degrees of knock. This part can typically be installed in under an hour".

He'* asking about a CAT BACK, 91PA, not a downpipe.

We also have members here that have PROVEN a loss in low-end torque by increasing the size of the DP too early in the mod game. In addition, the GP exhaust is quite different. We don't have the U-bend which further complicates things for them.