305 vortec to 350 vortec

[Schurkey]

I’m going true duals anyways.

That's a mistake.

 

[L31MaxExpress]

That's a mistake.

My 83 was from the factory, ran very well, although I had Dr Gas fab up a X-pipe for it in the earlier 2000s.

 

[Schurkey]

An X- or H-pipe makes the whole exhaust system more efficient. Effectively increases the muffler volume. The crossover in the intake manifold (where applicable) doesn't have enough flow capacity to make much difference.

As does a large-diameter single exhaust, at lower cost. But this somewhat depends on how many catalysts this truck needs.

 

[Erik the Awful]

Going true duals with no crossover is a mistake. Going to either duals with a crossover, or a y-pipe into 3" single exhaust, is recommended.

 

[L31MaxExpress]

Going true duals with no crossover is a mistake. Going to either duals with a crossover, or a y-pipe into 3" single exhaust, is recommended.

The most cost effective system I have found is dual pipes to a dual inlet muffler or dual inlet catalytic converter if the vehicle requires a single cat then a single or dual outlet from there. A merge Y closer to the engine ahead of the cat or muffler would probably be better, but a good merge Y cost as much or more as a good dual inlet muffler. With long tubes it is harder to get a good Y ahead of the cat or muffler on a shorter wheel base. My Tahoe responded very well to long tubes, 2.5" pipes with high flow metallic core cats, then a 2.5" dual inlet, single 3" outlet magnaflow. The 97 van essentially has the same setup, except it still has the OE dual 3" tubing to the muffler and a dual 3" inlet/single 4" outlet muffler. The 350 responded to tri-ys, the high flow cats, and freer flowing muffler on it like I was feeding it a small shot of nitrous.

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[Supercharged111]

Easiest would be to retune the stock computer. Pick up a bunch more power that way too.

 

[L31MaxExpress]

Easiest would be to retune the stock computer. Pick up a bunch more power that way too.

Intake, headers, exhaust and tune wake them up more than most give them credit. Something like a Summit 8800 cam would also do very well once the engine can actually breathe.

 

[Supercharged111]

Intake, headers, exhaust and tune wake them up more than most give them credit. Something like a Summit 8800 cam would also do very well once the engine can actually breathe.

I was thinking also to avoid whatever headache comes with that wonky O2 setup.

 

[L31MaxExpress]

I was thinking also to avoid whatever headache comes with that wonky O2 setup.

If he is ditching the Y-pipe anyway, should start with a 350 tune. Will make things alot easier.

 

[Supercharged111]

If he is ditching the Y-pipe anyway, should start with a 350 tune. Will make things alot easier.

Agreed, it all boils down to what exhaust he's going to run.