IDP Plenum question

I am interested in any direct experience you might have with IDP plenums. I have a 2003 c2, and the plenum and throttle body upgrades seem like a reasonable way to get a few more horsepower. Their literature states that all upgrades need to be accompanied with an exhaust upgrade, which I am not interested in doing. My question is this: Did Porsche change their exhaust system when somebody ordered the c2 with the x-51 upgrade? Isn't that the same basic c2 engine with only intake modifications by Porsche? Perhaps there is more to the x-51 upgrade. I have contacted IDP twice to talk to them about it, but have not received a response. thanks!

I have an 03 C2 with the IPD plenum and stock (non-GT3) throttle body / exhaust. It helps the sounds a little bit in upper rpms. Our patron saint of the m96 engine, FSI's Jake, has repeatedly noted that IPD plenums improve airflow for our cars induction. The X51 is complex package that includes internal engine upgrades, a better intake manifold, etc. It's a massaged engine in several respects. If you go to the IPD competition plenum and the GT3 ~82mm throttle body, then you have the potential for a lot more air. You may need a tune, but I'm not sure. It's certainly a step ahead of where I am with the stock TB. There are a few recent threads on this with good inputs if you take the time to read. I've tried to summarize what I can above. https://rennlist.com/forums/996-foru...pd-plenum.html https://rennlist.com/forums/996-foru...ttle-body.html gl-

If the engine remains stock internally, the IPD will help some with power, but stay away from the larger throttle body. Bigger is not better. In my direct experience I don't step up to the 83mm until we hit at least 3.8L, and preferably 4.0L. Its very easy to end up with "big throttle body syndrome" where the engine actually loses power.

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That is a surprise, IPD usually has great customer service. I have IPD comp w/GT TB, not recommended if you are not going to complete with an exhaust system and tune. Talk with them and focus on just a stock upgrade from plastic to aluminum. Also, change the CAI hose from air box to TB and get a BMC air filter. Check out Fabspeed for hose and filter. GL

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thanks for explaining, makes sense.

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I did a fair bit of research and bought a BMC filter but removed it. There were too many horror stories around cleaning, re-oiling and even one where the entire rubber element fell apart! Also the filtering capabilities didn't really impress me. In the end I just removed it however this is just my experience.

Hello - just to share my conclusion on the issue (for now, at least) - after many hours of reading posts all over the web! - I'm sticking with the original air box, with the Fabspeed modification kit (air intake kit consisting of the hose and air box plug only) + BMC filter (mine is of amazing, rugged quality - hope it holds up) + FVD tune and 200 cell cats/pipes. I do think enhanced headers would be nice some day (but, for now, I worry about obvious issues associated with original header removal - I have very bad luck with old bolts!). I sure like the idea of the enhanced plenum/throttle body, but I could never find definitive proof of any significant performance gain - maybe just 3 to 4 HP (or something like that). Thanks, Jerry

personally i think it is a waste of money if you arent going to do the exhaust and a tune. The m96 is hard to get more power out of just throwing a part or two at. Even if you do the "all in" approach if you do a before and after on the same dyno you want be terribly impressed with gain to money spent ratio.

" I don't step up to the 83mm until we hit at least 3.8L, and preferably 4.0L. " hey Santa...what's your Christmas Special for the additions above??? merry Christmas! m

the ipd plenum reduces restrictions to airflow that dynos do show to increase hp. the ipd dynos can be difficult to interpret, however, as the results they post often show the addition of tune and exhaust improvements as well. re the gt3 throttle body, think pipes and valves. if you have a 1" pipe with a 1" tap on the end, then 50% of the water is flowing through when the tap is half open, and all the water is flowing when the tap is fully open. if you have a 1" pipe with a 2" valve on the end, then 100% of the water is flowing when the valve is half open, and no more water after that. so, a larger throttle body will give a sprint booster type effect - power comes on sooner. next, think about how porsche tends to operate - they like to leave a little bit of power on the table so that they can increase the power for next year's model. without getting into the engine internals, you are looking at restrictors on intake, exhaust and tune. in the boxster world we've seen the 3.2 grow from 252 in 2000 to 266 in 2005 with just these changes (and variocam+). so, the pessimist says that your current intake is similar to a 1" pipe with a 1/2" tap on it, and you have some unrealised power available to you by adding a larger throttle body. true? dunno. it gets confused by the fact that on street cars porsche uses an intake system that decreases in diameter as you progress from airbox to intake - the decreasing diameter is designed to accelerate the air and facilitate cylinder fill so that torque is increased at lower rpms. this makes the street car more driveable but introduces restriction to max airflow at higher rpms. this is why the gt3 has the bigger throttle body - porsche wanted to make the airflow path as unrestrictive as possible for max airflow at high rpms for track work, but do sacrifice some low-end torque as a result - not a big deal on a 3.6 gt3 engine however. for comparison, on the x51 intake package they use a standard 996 throttle body and didn't see the need to increase diameter (they also use a standard 996 plenum, however, so perhaps they didn't want the 3.6 x51 challenging the gt3?).

SOLD - thanks!

Is it the one with the plastic coating on the inside, or the dimples and shot peened?

It is red paint on the inside, I think it predates the dimples. Thanks

If you are having trouble contacting IPD, pick up the phone and call Greg. He is incredibly passionate about Porsches and his product, and quite responsive.

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Surprised to hear the trouble of reaching IPD as well. Worst case scenario, feel free to give me a ring...I'm quite knowledgeable on their products as we are one of their largest distributors. Couldn't agree more

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PM'd if you still have it!

I have the IPD plenum and a K&N intake on my 2000 c4. I noticed a big difference with the intake. I noticed no difference with the plenum. Maybe I need a tune?

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Some ECUs adapt better than others to intake upgrades. Try unhooking your battery for 10-15minutes to reset the ECU learning, that may help. Tuning is always a great upgrade in itself, the bonus is we can optimize ECU mapping for hardware upgrades, including the intake side. I would be happy to set you up with a tune if interested, performance gains would be 10-15hp with a noticeable improvement in throttle response as well