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Discussion Starter · #1 ·
Has anyone ever done a test to determine exactly what the exhaust backpressure really is under different configurations, ie: 4" stock, no muffler, no cat etc? Seems like someone would be able to rig a boost pressure gauge after the downpipe to see if there's any backpressure at all. I don't have the equipment to do such a test but I'm sure someone has the means to see once and for all if there's a backpressure issue.
 

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There is going to be drive pressure in the exhaust manifold before the turbocharger that is on the same order of magnitude as the intake boost pressure; a turbo at 30 PSI boost pressure is likely to have drive pressure anywhere from 15 to 45 PSI depending on its geometry. Lots of guys watch drive pressure.

I would think that backpressure caused by mufflers, resonators or even catalytic converters would be insignificant in comparison. Any backpressure there would cause a direct increase to drive pressure, however, so you would want it to be little; I think you'd be hard pressed to find much over a couple PSI on any system, though.

I could be wrong. Would be easy to check.
 

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Discussion Starter · #3 ·
Yeah I was under the impression that the exhaust housing of the turbo would be the most restrictive part of the system. In reality I doubt removing anything would make a big difference unless you're replacing your turbo. The reason I'm asking is because I put a 5" with muffler on and hate the sound. I'm contemplating removing the muffler and replacing it with my stock 4" cat because I think it sounded better with the cat on the 4" system
 

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All I know about it is a few folks who run a pressure gauge upsteam of their exhaust brake.
They're checking to make sure they don't exceed 60 psi and float the valves.
None of the folks I know come even close, around 40 psi max with the brake engaged.
That's almost a complete exhaust obstruction, rpms may be up from a downhill but throttle is at idle.
 
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