I read at lancerregister that a decat decreased the low end/mid range torque: http://www.lancerregister.com/showth...hreadid=105605

I read here a good comparo about stock cat vs random 2,5HF cat vs decat and it seems that less back pressure is good for the low end/mid range power:
https://www.evolutionm.net/forums/sh...threadid=37340

What can I expect on the Torque side from a HF cat or a decat?

 

Found an interesting article:

http://people.msoe.edu/~lannanm/TECH...andtorque.html

 

im going for the hi-flo just for "some" BP and for legality issues as well.

 

You want no restrictions in your exhaust system (back pressure).
turning up the boost will bring up your torque... a high lift intake and short duration intake cam and smaller lift and longer duration exhaust cam will also increase your torque. A quicker spooling turbo and tubular exhaust manifold will do the same...

 

In a turbocharged system, the only place in the exhaust that you want backpressure is inside the exhaust manifold BEFORE the turbo.

The idea/concept that backpressure maintains a level a torque is only applicable on a naturally aspirated engine.

On ANY turbocharged application, you want the highest flowing exhaust system you can get away with for maximum horsepower AND turque. Obviously sound and emissions will factor into your choice, but from solely a performance standpoint, the highest flowing is what you want.

 

Thanks for the reply...

"On ANY turbocharged application, you want the highest flowing exhaust system you can get away with for maximum horsepower AND turque. Obviously sound and emissions will factor into your choice, but from solely a performance standpoint, the highest flowing is what you want."


Is this true if I maintain the stock boost pressure and/or do not touch the boost?

Will the peak torque appear in the same rpm with a high flow exhaust system?

 

Basically just use this concept when dealing with turbo cars..
Back pressure bad, open pipes or no pressure good.