maf and throttle body diameter

[The Radium King]

i was thinking 'de-tune' factor also, but why do it to the 996 (thier flagship at the time)?

anyway, the purpose of this thread was the same as you - some thought on getting a larger throttle body on my car. findings are as follows:

- there is benefit to doing this
- porsche makes two 3"-ish throttle bodies that match the 3" boxster maf diameter; a 74 mm (996, 987, cayman) and a 76 mm (996 gt3, cayenne)
- the 76 mm won't work; different plenum connection, more expensive.
- the 74 mm would work, but i am uncertain if the plenums would match exactly. even if they did, i am uncertain if you are not just moving the restriction further downstream as a result.
- so, you can use 996 plenum and two reducer boots (but would have to re-route the aos) or cayman (edit to add that i think the cayman plenum has a resonance flap that the 986 does not, as well as two aos connections instead of one); there should be lots of take-offs from guys who have put ipd units on their cars.
- note that you would also have to change the piping from maf housing to throttle body as it is currently sized for the smaller throttle body; you would need a 3" pipe/flex duct of some sort.

the next step in my thinking was having a go at the plenum. there is something inherently wrong in paying $900 for the ipd product; i was thinking of the following:

- get a cayman throttle body and plenum.
- saw the 'T' off the plenum, leaving only the flange and aos connection.
- get a silicone guy to fabricate a 'Y' with appropriate diameters.
- hose clamp it to your two intake runners and modified plenum.