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Torque box vs straight pipe

6K views 12 replies 7 participants last post by  jlh92 
#1 ·
On my 98 2.5 I recently changed out my intake "torque box"
for the earlier style intake piping that is just a J-shaped piece of pipe from the air box to the throttle body. I did this because I had heard that it was a freer flowing style.

Results: Throttle response seems to be improved, exhaust note has actually gotten quieter ( why I don't know), and now revving the engine produces that lovely CAI sucking noise.

Has anybody else done this or have any ideas why this simple change would produce such dramatic results?
 
#8 ·
The engine revs a lot smoother now than it did previously. I would say that low end torque did indeed improve, probably not anything that would be proved on a dyno, but having done this on two 98 legacy's I can say it does make them run smoother and better, even idle quieter.
 
#10 ·
No, sorry. I just got mine from the wrecking yard. I think there are 2 styles of the J shaped pipe as well. Also you have to hack up and do some really easy pipe fabrication to get all the Crankcase ventilation and cam ventilation stuff to connect up to the new one. It's a cinch though
 
#11 ·
does the engine sound any more grumbly/rumbly than before?
I was messing around yesterday and opened the filter box to see if I could hear some induction noise while playing with the throttle body and it made this really weird humming sound...byproduct of the resonant chambers in the torque box and noise tubes on the ej25d piping.
 
#12 ·
Eh, I don't know I have a muffler delete and I would say it is actually quieter. Not sure what exactly you're looking for...Ya the stock intake needs the helmholtz resonator in the fender for the intake to not do weird things. I tried going without that too, it did some weird things to the way the engine ran below 2,000 rpm.
 
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