Bolt on exhaust selection help for my 305.

[luconi]

Going to replace the entirety of my exhaust from manifold back on my 305. It needs to be replaced due to age and leaks.

Key Factory...I would like something that is all bolt in without any modifications. I don't mind a little bit of extra exhaust note but I would like to stay in a stock range of noise. My truck is a Daily.

I am keeping the stock exhaust manifolds since I just recently replaced them. #noimnotbuyingheaders

My current setup is the stock single catalytic converter that dumps into a single outlet pipe into the gigantic leaky OEM muffler. Nothing has been touched since the truck left the factory.

I am looking into "upgrading" to the true dual catalytic pipes from a 5.7 truck since those are plentiful in the aftermarket and getting stock dual outlet bolt-in cat back exhaust.

Will I have to modify anything to get this to fit? Will this bolt into the stock manifolds of my 305 and not get in the way of anything else?

Looking at the flowmaster cat on summit racing... Any suggestions on the catback? to spend around $500-600 for the whole shebang. Lower cost would be better. I want to keep catalytic converters.

 

[b454rat]

What year truck? sounds like a Vrotec, they only have a single cat. Running headers will wake it up, and not necessarily make it louder, that's what the muffler does. I have a 96 Yukon that I bolted on a set off Summitracing headers, Jeg's "offroad" (no cats) down pipes, all bolted on with no mods, and bolted on to the back half that is already a cat back. Its' got a rumble, but sounds great.

 

[luconi]

It's a 1998 (So yes, Vortec 305)

 

[df2x4]

Not sure about bolting a 350 system up to a 305 truck... I'd imagine it would work but you may run into issues with little PITA things like oxygen sensor placement. If you're buying an aftermarket cat back system with larger diameter pipes than factory anyway I wouldn't worry about it, just get whatever the catalog says fits your truck.

I've had a Gibson single 3" cat back system on my red truck for the past decade or so and I'm very happy with it. Definitely louder than factory but not offensively so.

 

[luconi]

Not sure about bolting a 350 system up to a 305 truck... I'd imagine it would work but you may run into issues with little PITA things like oxygen sensor placement. If you're buying an aftermarket cat back system with larger diameter pipes than factory anyway I wouldn't worry about it, just get whatever the catalog says fits your truck.

I've had a Gibson single 3" cat back system on my red truck for the past decade or so and I'm very happy with it. Definitely louder than factory but not offensively so.

I'm finding that the 5.7 exhaust kits have far more options available and are actually cheaper. There's not much available for the 5.0l... If I can get a little more power out of it and if i can confirm the 350 exhaust will bolt up and work I will be happy with that. The Gibson single is sweet, however it costs as much as buying a new Cat and exhaust system for just the catback.

I can deal with finicky things to make it work. I just want to confirm with people who have used 5.7L piping on a 5.0L to make sure everything will bolt up and work. I would hate to order everything and end up needing to return stuff.... It looks like everything is located where the 5.0L piping goes (flange locations, O2 sensor locations, etc...)

 

[alpinecrick]

The 5.7's have four O2 sensors. Don't the 5.0's with the single exhaust have three O2 sensors? My 96 5.0 Express is (I think) set up that way.

 

[b454rat]

I had a 96 Centurion that came with a 305, had single exhaust and one O2 sensor. Anything that bolts to a 350 will bolt to a 305.

 

[luconi]

The 5.7's have four O2 sensors. Don't the 5.0's with the single exhaust have three O2 sensors? My 96 5.0 Express is (I think) set up that way.

Damn... good point...
I started carefully looking at the difference between the 305 and 350 downpipes and the 305 actually has 4 O2 sensors (3 pre cat 1 post cat) and the 350 has 3 O2 sensors (2 pre cat 1 post)

How would I overcome this so I don't throw a CEL?

I need to keep my emissions stuff.

 

[alpinecrick]

Damn... good point...
I started carefully looking at the difference between the 305 and 350 downpipes and the 305 actually has 4 O2 sensors (3 pre cat 1 post cat) and the 350 has 3 O2 sensors (2 pre cat 1 post)

How would I overcome this so I don't throw a CEL?

I need to keep my emissions stuff.

My 96 and 97 k1500’s with 5.7’s have two pre cat and two post cat O2’s.
What might be misleading is one of the post cat O2’s is located in the “mid pipe” after the big flange that joins the down pipes to the mid pipes. It’s because one of the cat’s are located almost tight against the flange.

 

[L31MaxExpress]

The 5.7's have four O2 sensors. Don't the 5.0's with the single exhaust have three O2 sensors? My 96 5.0 Express is (I think) set up that way.

Has 4 02 sensors, but 3 of them are before the cat.