I see tons of post on it. I also see that its an exhaust pipe atleast from the pictures i found on google. anyway why is it so popular and what is the purpose of it?

 

Since the 3G or 3rd generation TL's have the header or exhaust manifold cast into the block. The catalytic converters attach to the engine directly and the J- pipe is the exhaust piece that connects the front and back cats to the rest of the exhaust system. The stock j- pipe is small and restrictive and the aftermarket ones are better designed and produce more power.

 

Side-by-side shows the restriction in the stock pipe:

 

after looking at that picture, almost makes me wonder why acura made the j pipe so restrictive from the factory. They possibly could of advertised the 04 TL as having closer to 285hp from the factory if they used a more free flowing j pipe

 

wow that really looks like a poor design on there part. looks like a real easy diy HP gain unless its really hard to get to.

Your response leads me to another question..so there is no manifold gasket? the manifold is built right on the block?

Do you have to remove at cat to install the j pipe and if so what about the o2 sensors and such?

 

The J-pipe connects the bottom or exits of the two cats. Unless your bolts are rusty it should be a pretty easy DIY.

 

took me about an hour in my garage on ramps and towers, go for it.......

 

Does any one kno if the pipe diameter is different between the alt jpipe vs the factory one? I have a 7th gen v6 accord so we too have the same restrictive jpipe

 

you can ask richie, he makes the accord and tl j pipes