Cat vs Hiflow vs Decat


i got a skunk2 hi flow cat on my type r eg and i did feel the difference on torque plus the whole catback sound way different is like more deep sound more aggressive.
 
Exhaust velocity is most important for making more power. When the exhaust flow is so smooth each exhaust pulse leaves a vacuum behind to suck out the next pulse so instead of the engine pushing the gases out the exhaust itself it is actually sucking out hence taking the load off the engine and reducing pumping losses. This is where exhaust piping is important, different size piping will give you ideal exhaust velocity at different RPM points. You can’t have perfect velocity throughout your entire rpm range. a smaller piping will give you better velocity down low but too small and your sacrificing top end power because your restricting flow, a large exhaust will give you that ideal velocity higher up in the power band but you may loose some power down low.

A decat pipe removes the catylic convertor. The cat is very restrictive in order to keep emissions down. The decat pipe is a straight throw replacement which allows the engine to breath better particularly at high RPM’s. How does it make power? Well as explained above it means the engine does not have to waste power and energy on “pumping” the exhaust gasses through the system hence making more power.
 
panic over just put some shell V power in my car after been running esso super unleaded recently and its going like stink again,, not gonna try the cat again til next mot...
 
olly ek9 said:
panic over just put some shell V power in my car after been running esso super unleaded recently and its going like stink again,, not gonna try the cat again til next mot...
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Makes a huge difference V Power. Even my R1 has started to get a taste for it... :angry:
 
I put my cat back in for the NCT and definitely noticed a drop,especially at crossover,I'll be leaving it in until after the test but its coming out the second I pass and the J's decat is going back in
 
ive got a 200cell sports cat, can see through it easy when its off, and ive got a full spoon system and trust manifold, and i must say it sounds amazing no rasp at all, and it passed its mot with it fitted....just!, but saves the hastle of putting normal cat back on, and gives just as good a gain as a decat, and sounds better if you ask me...
 
Thats where Im at with the whole Cat/De-Cat issue..

Tend to agree that my hiflow gives the best of both worlds.....Nice & free flowing; moreso than a stock cat, yet doesnt produce that tinny hollow rasp that De-cats seem to...:nice:
 
Decat for the win but................hows your MPG coming along? haha!! That's where I run a cat for mpg for the win! =P
 
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