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Thanks Keang24, I will try to have them changed to a resonated SS X pipes to try to reintroduce a bit more back pressure.
I think these engines need a certain amount of back pressure to give their best.:confused2
 

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so are you saying that the non resonated ss x-pipes will cause a loss of hp?
Not necessary, but it couldhmmm. Only way to find out is DYNO/DYNO/DYNO:).

I knew that the first RPI prototype of their x-pipe loss power, so he redesigned and test, test, test, until he came with the current design.
 

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Thanks Keang24, I will try to have them changed to a resonated SS X pipes to try to reintroduce a bit more back pressure.
I think these engines need a certain amount of back pressure to give their best.:confused2
By adding cats/resonators to improve back pressure is somewhat a misleding because it wil cost you some hp from those elements.

It better to go with no cats/resonators, but pipe diameter and shape have to be well designed to suit our engine. It has to be balanced between volumetric efficiency and Exhaust Gas Velocity (EGV). Here is a good article, The myth of exhaust backpressure - My Pro Street

:cheers:
 

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By adding cats/resonators to improve back pressure is somewhat a misleding because it wil cost you some hp from those elements.

It better to go with no cats/resonators, but pipe diameter and shape have to be well designed to suit our engine. It has to be balanced between volumetric efficiency and Exhaust Gas Velocity (EGV). Here is a good article, The myth of exhaust backpressure - My Pro Street

:cheers:
Sorry guys for going off topic. Kenny, I remember you saying something about replacing your Sec.1 ST High Flow Cats with Sec. 1 GT, have you? If you did how was the outcome (sound / performance). Thanks.
 

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By adding cats/resonators to improve back pressure is somewhat a misleding because it wil cost you some hp from those elements.

It better to go with no cats/resonators, but pipe diameter and shape have to be well designed to suit our engine. It has to be balanced between volumetric efficiency and Exhaust Gas Velocity (EGV). Here is a good article, The myth of exhaust backpressure - My Pro Street

:cheers:
Thanks Kenny. Long reading but very informative especially for ignorant people like me.:3:
 

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Sorry guys for going off topic. Kenny, I remember you saying something about replacing your Sec.1 ST High Flow Cats with Sec. 1 GT, have you? If you did how was the outcome (sound / performance). Thanks.
Haven't done on mine yet, but already been verified on one car that 8hp gain from swapping ST to GT. But the car sound very raspy. One car dyno is not enough, hope to get my done next week to gather more proven data.

Note: the GT section1 also was wrapped with insulated tape of some sort to keep the pipe from release the heat, so EGV (exhaust gas velocity) was increase as pipe getting constant heat. I think that how they do a custom pipe for racing. Probe the exhaust every 6inches to monitor the temperature. As soon as temperature drop, that where it start to slow dow the velocity. THe better you maintain the constant heat from the engine, the better flow of EGV and more power.
 
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