First of all, how come I never see Honda's or Acura's running 3" pipe. I figured because there would be a pressure drop due to the fact that most Street Honda's Turbo's are not big enought to warrant using this size pipe. And is there really any sense running a 3" pipe if the throttlebody is only 2.5 inches round. I also thought I saw a spot in my car where a 3" pipe would not work...anybody ever try to put 3" pipe on their cars?

I see a few problems with it, I know I would never do it.
First, the 3" pipe is heavier, and more expensive. There are better things to spend your money on.
Second, you're right, the 2.5in throttle body is a restriction the most amount of air that will get into your engine will be whatever you can push through there.
Third, even if you see any gains, I think it's going to get on the boost slower with an oversized pipe everywhere. The air will just have to fill up the extra volume before you develop pressure, too big of a pipe will just cause more lag.
Lastly, you said it yourself, 3" is a big pipe and is harder to work with than a smaller one, Since I bet not that many people have done it, it's probably alot more work than its worth.
If you were working on a Chevy 350 small block, a 3in intake might be benificial, or if you were running tons of boost with an anftermarket intake and throttle body, then sure, go bigger; but usually theres a reason that you don't see something on people's cars.

:2cents:
Buzz1167
Jon N

yea what buzz said having that big of a pipe without needing would cause more lag i was reading about a guy thats has an integra Ls with 515 hp and hes still useing the 2.5 piping and i think hes pushing like 31 psi so i dont see a need for it becuase most of use will never get that high

For starters, most hondas are running T3/TO4E or T3/TO4B hybrids with 2" or 2.5" outlets. Most people arn't going to throw 3" piping on there when 2.5" is obviously going to work fine. Personally I'm running a turbo with a TO4S compressor cover which has a 3" outlet, so I am running 3" compressor piping just so that there isn't a disruption of flow. I doubt you are going to see any serious inrease or decrease in lag by going up a half inch in diameter of charge piping.

good point

hey boosted....are you running just a full race turbo or the whole kit. Im selling my stuff to get a stage 4 kit from them.

Do you think having an ITR trans makes you car faster than if you had an LS? (i know..old ?)

Im definately gonna need 3" piping when I get the new kit cause of the size of the turbo. Did full race include your 3" piping and is it chrome or finished

hey boosted....are you running just a full race turbo or the whole kit. Im selling my stuff to get a stage 4 kit from them.

Do you think having an ITR trans makes you car faster than if you had an LS? (i know..old ?)

Im definately gonna need 3" piping when I get the new kit cause of the size of the turbo. Did full race include your 3" piping and is it chrome or finished

I'm running a full race manifold and full race T3/T67. Downpipe I fabbed up, exhaust is a kteller.com piping kit with an apexi N1, intercooler is a PTE "750HP" cooler, bov is tial, gate is tial 40. I had my charge piping powdercoated red.

With the ITR trans it feels much better than with the LS trans. Gets into boost faster in first gear, and it accelerates harder through every gear. Definitely worthwhile.

Edit: Forgot to mention I fabbed up the charge piping myself, had a buddy tig it up for me and bead the edges of the pipes. If you don't lay down a bead the connectors don't have anything to hold onto under heavy boost.