5.7 Stainless Y Pipe fit a 4.3 ?????

[Crank1]

Hey guys. I'm looking to go full stainless exhaust one day. and just had this annoying question in my head. I havent seen a stainless Y pipe for the 4.3 vortec. Do the manifolds dump in the same place on a 5.7 and 4.3??? I also want to add the JBA headers to it, which should replace the factory manifolds and are the same size. I am just wondering now, does anyone have either truck that could tell me??? Or compare? Thanks
Brandon

[CKTA]

1. The manifolds dump in the same spot. However, the 5.7 Y- is different because it has 2 cats. vs. your one. Maybe a 5.0 one will work. :dunno: That has 1 cat.

2. The JBA's will bolt up to the factory Y or aftermarket one that will bolt to stock manifolds.

[jerome99]

what year is your 4.3 cuz mine has two cats I have a 03

[CKTA]

He says he has a 5.7 vortec...so it has to be a '96-'98.

[Crank1]

Sorry for the confusion. I only have the 4.3L Vortec. '98 Cheyenne. Okay, so if I was custom making my own exhaust from the Y back, including a stainless high flow cat, I could in theory use the 5.7L Y pipe? Thanks for the reply
Brandon

[Pauly]

Ther is no 350 Vortec y-pipe. The factory used 2 seperate crossover pipes which fed 2 seperate catalytics. The stock L31 350 Vortec crossover pipes are 1 7/8" tubing, fine for you 4.3 but not a 350. The stock vortec 350 cats actually flow quite well, its the stock headpipes that are a restriction on any 350 vortec. The factory Vortec 350 L31 headpipes crimp down markedly on the drivers side 90 degree bend. I have had a custom dual 2.5" stainless setup aftermarket 2.5" dual cats , 2 in 2 out muffler into dual 4 inch stainless ends that exit infront of the pass. side tire.

The y-pipe you have, if its a single cat is either from a vortec 305 96-99 or vortec v6 96 up, or its a TBI y-pipe.

Hope this helps.

I still have the stock L31 crossover pipes and cats in my shed, if you need any measurements.

Pauly

[97Silverado]

Ther is no 350 Vortec y-pipe. The factory used 2 seperate crossover pipes which fed 2 seperate catalytics. The stock L31 350 Vortec crossover pipes are 1 7/8" tubing, fine for you 4.3 but not a 350. The stock vortec 350 cats actually flow quite well, its the stock headpipes that are a restriction on any 350 vortec. The factory Vortec 350 L31 headpipes crimp down markedly on the drivers side 90 degree bend. I have had a custom dual 2.5" stainless setup aftermarket 2.5" dual cats , 2 in 2 out muffler into dual 4 inch stainless ends that exit infront of the pass. side tire.

The y-pipe you have, if its a single cat is either from a vortec 305 96-99 or vortec v6 96 up, or its a TBI y-pipe.

Hope this helps.

I still have the stock L31 crossover pipes and cats in my shed, if you need any measurements.

PaulyYou are technically correct but because it is a single assembly it is commonly referred to as a y-pipe.

[Pauly]

You are technically correct but because it is a single assembly it is commonly referred to as a y-pipe.
You are correct my friend, because it looks like the shape of a Y.

[Crank1]

Ah, I see now, The Y pipe I was thinking would work was like only up to 95. Thanks for the offer for the measurements, but whenever I strip my exhaust, to go full stainless, I'll just use mine as a template, but what size would anyone recommend for a 4.3, I want it to flow, but not be too open.. Thanks
Brandon

[no2guncntrl]

2" or 2.25" on the banks going into a 2.50" merge pipe
for the 02 to cat. SLP used to make a super nice y-pipe
for the 4.3 S-truck but have stopped doing so.
They are like gold for the lil trucks.

Since your truck wgt is heavier than an S-truck 2" for the banks
would more than likely be ok so you can keep a bit of your lower
end or torque. You'll lose some low end with the JBA's. Not much
but I could sure tell. However once past 2600 on up things get
going a bit quicker..HTH's