5.7L Vortec Catalytic Converter Question

[Ben Burrage]

What is the OD of the pipe on those? When my Tahoe had the 305 in it, it had BBK shorties and Magnaflow (Bosal are the same) cats for a 5.7 2500 Suburban with the 2.75" pipes. Dual 3" in, single 4" out muffler. Re-used the same cats and rear pipes with Edelbrock headers and upper headpipes that welded to the front of the cats for an 8.1 Avalanche or Suburban when I 8.1 swapped it.

Appear to be 2.75. Flows great

 

[Hogg]

Never had a tbi 5.7. Only vortec. That said I dont see why the bosal couldn't fit tbi. However I know back then the factory came with 1 cat. Then in obd2 or vortec they came with 2 cats. Not sure why. This set up is factory though and i love it. My thought is this cats will fail so want to be able to change that. Muffler will get replaced eventually so same story. My plan is this. Have factory set up cats. Then i want a new aftermarket exhaust system that still bolts to the cats. Might be custom but dont care. Then i want the 2 pipes to flow to the rear over the axle under the rear panel. But instead of going out the side I want them straight back and angle down. That's my ideal exhaust system. As far as quality aluminum or stainles . But really want stainless.

4.3/5.0 L35/L30 had single cat like TBI 4.3/5.0/5.7, but Vortec 5.7/7.4 had dual cats. The LD and HD 5.7 L31 trucks also had different pipe sizes off the manifolds 1-7/8" vs. 2-3/4 for the over 8600pound GVRW trucks.

peace
Hog

 

[SUBURBAN5]

4.3/5.0 L35/L30 had single cat like TBI 4.3/5.0/5.7, but Vortec 5.7/7.4 had dual cats. The LD and HD 5.7 L31 trucks also had different pipe sizes off the manifolds 1-7/8" vs. 2-3/4 for the over 8600pound GVRW trucks.

peace
Hog

That's interesting. Never really paid attention to the sizes

 

[L31MaxExpress]

4.3/5.0 L35/L30 had single cat like TBI 4.3/5.0/5.7, but Vortec 5.7/7.4 had dual cats. The LD and HD 5.7 L31 trucks also had different pipe sizes off the manifolds 1-7/8" vs. 2-3/4 for the over 8600pound GVRW trucks.

peace
Hog

Found out that some of the 350 Vortecs had single cats recently too. Also some 2 door Tahoes and Vans had dual cats into a factory Y-pipe.

My 7,100 GVW Express van had dual 3" to the muffler as well.