mbpa

After following the many posts on exhausts, I am still confused about what the difference between them is and which pieces are exchangable across the systems. I have a Bishoff muffler but my stock tips say Gilette, so clearly at that stage parts are the same. Reading through old posts, it appears that at some points connections are different. But where?

So, going back toward the engine starting at the tips, which parts are the same and which are different -- muffler, cat, heat exchanger, etc?

993inNC

Mufflers are the same (generally), the difference is the connection type. Bishoff style has the ends flared to accept either the seal ring (also called a Buick Ball end), the gillet has the ball built into the piece and no sealing ring is needed. As far as the heat exchanger side, the bishoff is an oval opening with a non equal triangulated mounting, gillet has a round port with equal triangulated mounting holes.

mbpa

Thanks. That's clear.

What still confuses me though is that when people advertise their after-mkt mufflers (supercups etc) they generally don't mention Bishoff vs Gilette. Does that mean that the same after-mkt muffler will fit either?

Paulsha911

In the case of GHL, they ask you which version you have so that they can decide what to send you...

Kigiin

I own supercuppers and it didn't matter.

Rob

993inNC

Yes. If you have a bishoff style (flared end) cat (where the muffler connects), then you'll need the seal rings (Buick *****), if you have the gillet style (ball'd end) cat (where the muff connects) then no ring is needed and it bolts right up. This is assuming that the aftermarket stuff is supposed to be used in conjunction with factory pieces. Some of the newest stuff out there requires that you use their headers with their mufflers, catalytic converters etc....

Any clearer?

Paulsha911

If it doesn't matter, it would mean that the connection to the cats is the same for both Bishoff and Gillet. Is this right?

For the Supercup, it doesn't matter on the "tips" end because the tip is integrated and straight. But you'll need to figure out whether you need the donut gaskets or buick *****, if your muffler and tips are separate pieces. If you have Gillets, that would mean you do NOT have the buick ***** in your car because they are integrated. If you have Bishoff, then you probably already have those gaskets connecting between the mufflers and the tips.

BTW, those Buick ***** are not cheap. I ordered a pair and they were almost $80 with the PCA 10% off.

993inNC

No, again, if you have the bishoff....you have the flared end cat. Gilllett, you have the ball end. No ball on cat, needs sealing rings. Ball on cat, bolts right up (muffler has the flare instead).

Pelican has the sealing rings (buick *****) for like $30 a piece, where did you get yours?

Paulsha911

Got mine from the local Porsche dealer. Price included special handling for next day delivery ($7).

Bill Verburg

Besides lids I also have the market cornered on mufflers,
Here is a pair of Bischofs next to a pair of Gilettes, you can see that the inlet sides are the same, the difference is on the outlets


and a close up of the connectors w/ a Bischoff donut which is also used on the Gilette inlet side

ceboyd

so what years was what?

mbpa

Thanks Bill, the pictures helped clear up my confusion.

Bill Verburg

The Bischofs are oem from my '95, they show what serious weight reduction measures the p/o went through

the Gilletes are from a '96 and '97 it's interesting to compare the finish on the 2 sets of Gillets that I have, the late set looks the same as the '95 Bischof. The early set(not pictured because they are on the car in preparation for the noise ***** at LRP) has a polished ss case

It will also be interesting to hear the noise differences, the Bischofs are by far the lightest(and nosiest at ~98dBA), the late Gilette(RSR modified) is in the middle and the early Gillete(stock) is the heaviest and quietest @~87dBA.

ceboyd

so the gillet mufflers are heavier and quieter? I wonder what that says about my 'motor sound' gillet mufflers then?

Bill Verburg

Not necessarily

one pair of Gilletes is stock, the other was modified by Robin(RSR)

The Bischofs, may have been more radicaly altered, all of the external braketry has certainly been removed, I have no certain knowledge of what may have been done internally, but they are certainly louder than the RSR modified Gillets. They are also very light