Recently I purchased an empire performance exhaust for pretty cheap. When I installed it with a test pipe on the X, it was obnoxiously loud. So I took it into an exhaust shop and got a Magnaflow 3" to twin 2.5" muffler installed in it instead of the little useless mufflers already on there.

I further got a Wastegate, BCS and CAI

Problem came when during tuning, I was informed that the exhaust was placing a huge restriction on the flow and the figures I got were 220kW,520Nm instead of the expected 240-250kW,560Nm.

An obvious contribution to this problem was that I didn't change the downpipe.

Question is, how bad could the muffler have been in contributing to this power loss? Or was it largely the fact that downpipe was restricting the entire exhaust?

 

For the least restriction for turbocharged cars it is suggested to have 3" from the turbo out. With these cars from what I have read the only real need to change out the downpipe is when you go to a bigger turbo. With that being said if you went from a 3" to a 2.5" dual muffler setup then you have restricted the exhaust at that point which restricts the exhaust from finding the fastest way out.

 

Exhaust is the issue your downpipe is fine.

 

3" inlet with dual 2.5" outlets on the muffler is fine.


Why did you buy a wastegate? Do you mean wastegate actuator?

 

I meant actuator***

But I tried to find a 3inch to dual 3 inch out and multiple exhaust shops confirmed that the magnaflow was the best one available since dual 2.5 inch out is better than single 3 inch out anyways. Its hard to believe such a big company would create a **** muffler for around 450 AUD.

 

I don't think that's the issue, I think how the exhaust place you had fabricate it may be the issue. There might be some restrictions in the flow that you can't see from the outside.

 

Yeah for now I have just settled for the current power level. It is fast enough for daily use and sounds great tbh.

 

Then don't sweat it and enjoy. Numbers are just numbers I don't even remember my exact dyno to be honest and just enjoy the car lol

 

If you feel the Magna Flow is the problem, then just order a different one, there are tons of better choices.