PontiacBonnevilleClub.com

I just realized this morning how often members ask their OEM exhaust component diameters. Considering the simple setup of the 2k and newer, it's easy to forget there were some ODD configurations (more on that later) in the earlier years. I'm going to do a quick visual diagram of each exhaust layout for Techinfo based on year/engine/options so people can do a one-quick-glance and know what they have while planning a performance exhaust.

I'd like to base this on ACTUAL measurements even though many of us know the many configurations. So even if you KNOW, please measure. I'll start with both of mine today (and my 95 is one of those odd ducks I spoke of). If you'd like to help, please copy/past below, reply to the post, and fill in your info, and let's concentrate on 87-2005. If you have a 'cousin' H body, please contribute also, and if your configuration/layout is different than a Bville of the same year, please provide a simple sketch:



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OEM exhaust configuration/sizes
Year:
Engine Code:
Model/Trim:
Cat inlet diameter:
Cat oultet diameter:
Resonator inlet (if equipped):
Resonator outlet (if equipped):
Y inlet (if equipped):
Y oulets (if equipped):
Muffler inlet diameter:
Muffler outlet diameter:
Tip PIPE diameter (measure at the last round section if squared at the end):

I'll assemble the data into an easy to read chart, and sketch up some basic diagrams for a Techinfo article to help the noobs in the future.

While I have my car on the lift, I'll measure this for you.

Year:
Engine Code: L67
Model/Trim: SSEi
Downpipe: doublewall 3" OD / 2 1/2" ID
Flex connector: 1 3/4" ID
Cat inlet diameter: 2 1/2"
Cat oultet diameter: 2 1/2"
Resonator inlet: 2 1/2"
Resonator outlet: 2 1/4"
Y inlet : 2 1/4"
Y oulets : 2"
Muffler inlet diameter: 2"
Muffler outlet diameter: 2"
Tip PIPE diameter : 3" x 6" cowbell

Paul, the outlet tip BEFORE the cowbell. Some neck down or change shape (92-95) before the actual tip. Does the pipe stay the same diameter on the muffler outlet all the way to the weld at the cowbell? That's the number I'm after really (for those that want the diameter for the purpose of tips).

Yes Bill the 2" pipe is welded into a socket in the aluminum casting.
The casting has a bored hole that is 2" on the inlet and transitions to the rectangular 3" x 5" top cord & 7" bottom cord width outlet.

2000Silverbullet wrote:Yes Bill the 2" pipe is welded into a socket in the aluminum casting.
The casting has a bored hole that is 2" on the inlet and transitions to the rectangular 3" x 5" top cord & 7" bottom cord width outlet.

Yep, I second that.

Bump. How about some other years? Specifically the 95-99 L36, 2000-2005 L36, L27 (which varies by trim), 87-91, etc.

I'd like this to be as complete as possible.

Year: 1996
Engine Code: L67
Model/Trim: SSEi
Cat inlet diameter: 2.5"
Cat oultet diameter: 2.5"
Resonator inlet (if equipped): 2.5"
Resonator outlet (if equipped): 2.5"
Y inlet (if equipped): N/A
Y oulets (if equipped): N/A
Muffler inlet diameter: 2.5"
Muffler outlet diameter: stock is 2.25" flowmaster crossover muffler is 2.5"
Tip PIPE diameter (measure at the last round section if squared at the end):dont have access to factory tips

Example of what I'm up to here:



For each engine/year combination.

The 2000-2005 L36 exhaust is the same as the L67 as far as I know since mine used to have the L36 to start with and still has the same exhaust on it and has the same measurements.

Jared, are you sure it doesn't neck down to 2.25" anywhere before the Y? I'd expect the L36 to be smaller than the L67 at some point, much like the L27/L67 relationship in the Series 1.

I still need a 96-99 L36, an L27 or two, and maybe some help with the 87-91? Once I have that, it won't take me long to finish this up. This will be a very valuable techinfo article to steer members to with exhaust questions.

All the 00 NA Bonne's I've seen only have a single exhaust.

Except the SLE, which has dual outlets. But I bet the dimensions are a little different.

Still need the GXP also.

My bet is the SLE and SSEi dual exhausts are identical.

I always wondered why the twin pipes were only 2"

Yeah, the SLE is the same as the SSEi even with the L36. Maybe the SE is different?

great job bill looks great did you think about checking aftermarket mufflers and stating their inlet/outlet diameters? as i do know that the inlet outlet on the flowmaster crossover mufflers is 2.5" single inlet and dual 2.5" outlet.

but all in all that diagram is a great way to help people decide on their exhaust tuning choices

edit: by the way bill this might be a good reference but auto parts stores should have booklets from exhaust companies like walker, flowmaster, magnaflow, etc. (pepboys had them when i worked there) and these give exhaust part numbers and specs. might be a good place to check for those more tricky cars?

All major muffler manufacturers for the 92-99 'crossflow' generation are easily and readily available in 2.25", 2.5", 2.75", and 3.0". Very easily cross-referenced online.

www.justmagnaflow.com for example.

This is intended as a guide to selecting proper component sizes, not for sourcing components. We prefer people post when it comes to choosing brands/retailers, as sometimes this information goes stale and needs to be updated as we find new and/or better sources. That's constantly evolving information, where the OEM exhaust sizes don't change and should be documented for use this way.

Bill, this is the diagram for my 89 from the FSM. Mine is exactly like this. I will get measurements for you on sunday when I get off work. It does look like it is 2.25 for the whole system though.

Thanks, Matt. The diagram helps alot, and I'd expect it to be 2.25". I'll wait for your confirmation.

I expect the SSE is similar to the 92 and newer SSE/SSEi. Don, can you confirm that with yours?

so do you need the dimensions of an 00+ SLE?