Plenum and TB Upgrades SPECIFICALLY on Bored-Out m9x

I�ve done my review of the many threads on the popular IPD plenum and GT3 throttle-body upgrade and I�m still a little confused as to whether or not they actually impact performance, and more importantly, if they�d be a benefit for MY specific build. Again, I�ve searched/read/still a little confused. I�ve read they only add power with a tune, and only with supporting mods like a full exhaust/less restrictive cats, but I�ve also read they don�t really do anything tangible or functional for a street car (it�s all top end/ultra high rev stuff), even with those supporting parts and a tune. My engine builder says they�re really just dyno pleasers and not particular beneficial for a street car, even one I rev out often. My car is a 2000 6-speed car that�s had its OG 3.4 rebuilt as a 3.8 and has had the heads done by Len Hoffman with his porting/polishing/racing valve springs/etc. Currently running stock exhaust/cats/headers/air-box/tune. I�m throwing an air-box from a 3.8L 997S on it this week (mostly bc it looks better, but any extra induction noise/flow gains would be cool), and I�m going to do a Kline exhaust and 200 cell x-pipe eventually, and doing a Softronic tune. Is it worth throwing the upgraded plenum and TB on as well, or is it a waste of money? Will they rob low/midrange power/torque for the high end at all?

Quotes source post: 19958464

I have a 3.4 to 3.8 bored m96 that was done by Vision and I added the FVD bored TB and IPD plenum at same time. Additionally, I also added harm. balanced underdrive pulley and rennline carbon intake. With the motor being new, there was an increase in throttle response and intake noise but hard to say the impact. Once I got on Top Gear headers, 200 cell x pipe and their sport cans (added bypass to the cans for extra effect) that seemed to pull it all together and add on more top end power from ~3k onwards. I did pull in the tune last year (99 99 has a wonky dme) with a company in Arkansas to match the fuel trims of the 3.8. I would say go for it- the 3.8 does breathe considerably better with the exhaust and the bored TB from FVD port match the IPD plenum. Worth the investment at least on the TB, IPD plenum is still out for debate in my opinion. Supposedly Jake Raby is working on a m96 intake and runners to compliment their headers and x pipe!! First of its kind since maybe RUF with their turbo items and is supposed to flow better than the X51 upgrade.

@Murphey Parker right on. Thanks for the reply; that makes sense to me. My overall takeaway has been these parts do add power with a big bore build and supporting mods, but don�t do much for a stock m96 with other bolt-ons.

Quotes source post: 19958539

Correct- and if you can even find a X51 intake they are extremely rare on the used market. FVD has lots of cool parts so worth checking their catalog from time to time. You can compliment your 3.8 box ( I really want one as the 3.8 badge to match is just plain cool) with a drop in dry flow filter from AEM, etc. for maintenance free, better filtration than an oiled filter like K&N which can affect the MAF sensor. I am debating on a more aggressive muffler- like a after hours, etc but the drone is really worrying me... I can add some Helmholtz resonators and try the quarter wave cancel but the x pipe sound from a larger m96 is pretty glorious. High pitched/ great note and I ceramic coated my headers and x pipe to help with heat absorption. Plus, dropping extra lbs. off the rear end is also a plus! After hours has a Gen 2 wife friendly model I might test drive...

A larger plenum and throttle body that does NOT have a wedge interfering with the resonance waves bounding back and forth in the intake manifold will make about and extra 3-5hp consistently on our engine dyno.

Quotes source post: 19959689

Is there a brand/combo of parts you specifically recco here? Can�t say 3-5 hp is really worth the squeeze for a spicy street build.

https://www.ebay.com/itm/40564750478...mis&media=COPY this is what i got--it was very nicely made. granted i have a 997.1, so check if the 996 can use the same part.

Quotes source post: 19959689

What displacement produced those results?