PontiacBonnevilleClub.com

no beer involved in my wrapping, but it sure looks like there was

i will agree with everyone else though, the exhaust on a Bonneville is not very restrictive anyway (with the exception of the manifolds)

I've only noticed that Fords have exhaust issues. Both of my Bonnevilles are running just fine with OE cats. Yes, both can run. Even the 94. I have only had numerous exhaust issues with my parents' Fords, especially the Mercury Sable. It so badly clogged up both OE catalytic converters before 120,000 miles that we just cut them out. Its case is one of few that I consider all right to consider cutting out the cats. It runs so rich all the time, even after having all its sensors replaced and all the manifolds cleaned that it would just kill another cat. If your car is in such horrible condition that it destroys itself, you're perfectly welcome to remove the parts being destroyed. Otherwise, leave the cat on. A high-flow one would be really nice, though.

someone i know took his cat (or cats i'm not sure) off his 96 F-150 and he gained about 4 mpg

it was probably clogged

yeah but remember my car has 150,000 miles on it even with seafoam i imagine its not in the greatest shape

swampthing wrote:yeah but remember my car has 150,000 miles on it even with seafoam i imagine its not in the greatest shape

So replace it with a Magnaflow High Flow unit. It gives you more flow, while still maintaining legality and sound characteristics. We can't help you if you don't listen to us. And asking questions does no good if you don't listen to answers.

Many of us have run without a cat for some period of time. And we're all telling you the same thing. Go hi-flow unless you're building a 12-second daily driver.

ok look I would like to clarify something first I already accepted what everyone recommend as being the best course, however I continued disscussing because some other people brought up some points that were of interest to me I am not an idiot nor someone who likes being dogmatic I am not still trying to chop the cat and I certainly don't want to be rude to anyone that would defeat the point of posting questions in the first place.

Overall, it's cheaper to cut out the catalytic converter, but the forum's finds have been that a Magnaflow high-flow will not impede the exhaust flow of a 3800. Fords and such have a terrible time with cats and have more than one, but the 3800 is so efficient that it has a single cat for all 6 cylinders. The stock one is good enough, but going to a high flow is even better.

If you cut out your cat, you'll get a code on your dash. Intense and other PCM people can take out from your PCM the part of it that looks for a rear O2 sensor. It costs about $20, so the high flow cat is really that much more expensive. We've been using the Sable without catalytic converters for quite a while, and aside from the raspy sound and the better pickup, it's still as horrible as it ever was. Your Bonneville is nice, though. I think what people here have been trying to say is that you should leave it nice and do mods properly instead of cutting out the cat, the equivalent of slicks on a 14-15 second car.

swampthing wrote:yeah but remember my car has 150,000 miles on it even with seafoam i imagine its not in the greatest shape

seafoam will make the cat worse if anything

hey guys, what are the stock pipe sizes in a 2000 ssei? i'm trying to price a cat and mufflers


(new topic merged back into your other exhaust topic by Admin)

the stock size for bonnevilles is 2.5" into cat, 2.5" all the way back from there. most of us 92-99 bonnes run the magnaflow (carsound) cat found o ZZP and Intense and then flowmaster 80 series crossover muffler (F-body muffler used on camaros and firebirds) on the 2000+ they used the same cat but with mufflers it differs they have a little more options. i have seen 80 series flowmaster mufflers and magnaflow mufflers

To prevent confusion here, the 2k and newer run two seperate mufflers after the Y. Not a crossflow.

Furthermore, 'most' of the 92-99 Bonnevilles here do not run the Flowmaster series of Mufflers. The slight majority tend to prefer Magnaflow. The slight Minority seem to prefer Flowmaster.

However, the 2k is going to be quite a different animal in sound and resonance with the same brand as mufflers when compared to a 92-99 (or even 87-99) due to the very different configuration.

i thought after the resonator on a 2000+ the y-pipe was a smaller diameter like 2 1/4 pr something

Exhaust mods can be a very personal choice depending on the sound you want.

The closer the exhaust is to the engine heads the more effective improvements will be.

Start with headers and end with the tips (unless you want looks only)

Before I say more about deleting the Cat, I have to say I have never installed a performance Cat.

I have always cut them out and used an "Off-road" pipe in their place.
I have always seen both performance and mpg gains.
It increases the loudness of the exhaust significantly. Just like removing a muffler.

The stock SSEi pipe is 2.5" up to the inlet to the resonator. It exits the resonator at 2 1/4" and then splits into twin 2" pipes.

For your mods, I would recommend a Magnaflow performance Cat.
Work on your exhaust headers and downpipe.

The stock downpipe flex connector has a 1 1/2" hole in it. VERY restrictive!
You would never know it because it is a double walled pipe and measures 3" OD.

2000Silverbullet wrote:Exhaust mods can be a very personal choice depending on the sound you want.

The closer the exhaust is to the engine heads the more effective improvements will be.

Start with headers and end with the tips (unless you want looks only)

Before I say more about deleting the Cat, I have to say I have never installed a performance Cat.

I have always cut them out and used an "Off-road" pipe in their place.
I have always seen both performance and mpg gains.
It increases the loudness of the exhaust significantly. Just like removing a muffler.

The stock SSEi pipe is 2.5" up to the inlet to the resonator. It exits the resonator at 2 1/4" and then splits into twin 2" pipes.

For your mods, I would recommend a Magnaflow performance Cat.
Work on your exhaust headers and downpipe.

The stock downpipe flex connector has a 1 1/2" hole in it. VERY restrictive!
You would never know it because it is a double walled pipe and measures 3" OD.

thanx for the info, i would like to change the dp but they are expensive for what seems like a 3 inch pipe. i was thinking a power log and a ported rear manifold would be nice in the long run, right now i am just brainstorming as i am completely broke

If you are completely broke, the best bang for the least buck is killing your cat cut it or gut it

...but you did't hear that from me.

<------R.I.P CAT "who's idea was this?"

If you really do take out the cat, please make an exhaust video.

whatever i do i will make a vid