Exhaust Upgrade
Discussion
Funky said:
GreenV8S said:
What sort of answer do you think it would be possible to give to such a vague question about such a complex and subjective topic?
Call me crazy but i have already had people tell me a rough guesstimate about the % effects of sound level of a decat and backbox, i was looking for the missing piece of the manifold and its effects. I stated all the way through its just a total vague, "what do you think" kind of answer i was looking for. Is it ok now to stop shaming my question, despite me apologizing for not being clear enough in the beginning, or would you rather continue? As for me i am done and sorry i bothered to try pistonheads again after so many years. Obviously you need to know exactly what your talking about in great detail to be able to post questions here
Every single part of the exhaust system has effects, there is no "rough estimate" so those who have given you this information are talking out of their @rse.
Some cats are in the manifold so changing for a tubular will give a decent bump in noise.
To get proper power, it needs to be a tuned manifold so the runners are a specific equal length to create scavenging. Scavenging is using the engine pulses to create suction in the cylinder, so aids filling. There's others types too, but that's the main one. This can lead to quite long headers, so the pulse (piston stroke) is sucking whilst the last exhaust stroke is exiting. This is for NA cars. Simpson, Edwards, BTB etc..
Turbo cars it doesn't really matter about header length, the turbo is as close as possible and is the biggest restriction so the cat is usually found a bit further away, though can be very close to the turbo. Removing the cat will release noise, but the turbo will still quieten things down. People add X or H pipes to turbo cars to create scavenging sand balance the banks on bigger capacity cars and also contributes to noise.
I put an arrow can on my KTM and took the baffle out, it sounded great. But when I fitted a decat I put the baffle back in because it was too noisy.
On my Porsche I decatted the Tubi, but couldn't be bothered with getting a friendly MOT garage, so bought a switchable exhaust with a CAT, I still got plenty of noise, bit could turn it off when I wanted such as motorway cruising where the drone was horrible.
My GTR had a very expensive Kreissieg which screamed and sounded amazing, but was also switchable to quiet. This was the best exhaust I have even had, but it cost 12k dollars.
I had an old Celica that had a cheap powerflow, that was nasty on the motorway and I had to wear ear plugs.
I could go on, but you get the idea.
To get proper power, it needs to be a tuned manifold so the runners are a specific equal length to create scavenging. Scavenging is using the engine pulses to create suction in the cylinder, so aids filling. There's others types too, but that's the main one. This can lead to quite long headers, so the pulse (piston stroke) is sucking whilst the last exhaust stroke is exiting. This is for NA cars. Simpson, Edwards, BTB etc..
Turbo cars it doesn't really matter about header length, the turbo is as close as possible and is the biggest restriction so the cat is usually found a bit further away, though can be very close to the turbo. Removing the cat will release noise, but the turbo will still quieten things down. People add X or H pipes to turbo cars to create scavenging sand balance the banks on bigger capacity cars and also contributes to noise.
I put an arrow can on my KTM and took the baffle out, it sounded great. But when I fitted a decat I put the baffle back in because it was too noisy.
On my Porsche I decatted the Tubi, but couldn't be bothered with getting a friendly MOT garage, so bought a switchable exhaust with a CAT, I still got plenty of noise, bit could turn it off when I wanted such as motorway cruising where the drone was horrible.
My GTR had a very expensive Kreissieg which screamed and sounded amazing, but was also switchable to quiet. This was the best exhaust I have even had, but it cost 12k dollars.
I had an old Celica that had a cheap powerflow, that was nasty on the motorway and I had to wear ear plugs.
I could go on, but you get the idea.
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