Help with muffler size

[ledzz1]

Hey guys
My setup is 300whp

My manifold is stock

This runs to a 2.75' downpipe and 2.75 exhaust piping to the muffler that steps up to a 3' muffler with no restrictions at all due to it essentially being a straight pipe

Will the step up from 2.75 to 3 effect anything?

Please help
Thankyou

 

[Alkoran]

you won't flow enough to see any gains

 

[akiraproject24]

I run something similar. Its a Milltek DP (i think its 2.76) into a 3 inch Thermal but the Thermal meets the DP at less than 3 inch bolts right up though. Does it effect anything? She's OPEN wider than needed and I don't think it hurts anything. I also have a ported manifold and hybrid turbo.

 

[ledzz1]

you won't flow enough to see any gains

This is already fitted
Any downsides to this?
Exhaust velocity lower?
Would there be less back pressure

 

[Alkoran]

For a muffler that is 10 feet down the line, I don't have any scientific proofs but my gut is telling me you won't see any difference for that light of a change.

 

[Dialcaliper]

For a muffler that is 10 feet down the line, I don't have any scientific proofs but my gut is telling me you won't see any difference for that light of a change.

This is the right answer - anything as far back and short section as the muffler won’t make any appreciable difference in flow. If it’s a straight through, it might be imperceptibly louder, but it depends more on the muffler body size than the inlet/outlet - chambered mufflers will be even more similar. Stepping down to 2.5” might make a bit of a choke point, but not as much as you’d think.

Don’t sweat it, as 2.75” mufflers are not that easy to find anyway. Also keep in mind that piping sizes are measuring the OD, and the ID is smaller - a 3”ID muffler will slip right over a 2.75” OD pipe for a slip fit connection using a clamp.