NMSTT

Hey all,

I'm browsing around all the different performance part options for a new to me 997.2 GTS (PDK) and happened upon a 3.8L IPD plenum upgrade that claims 15hp over stock. I haven't been able to find any thread topics that address the viability or need for an upgraded IPD for an X51 equipped car like the GTS. Any tribal knowledge or examples of this being installed that any one is aware of? Thanks for all the knowledge,

http://competitionmotorsport.com/ipd...arrera-s-3-8l/

Nick

Crester

I bought an IPD Plenum for my 997.2 C4S... and honestly... I'd say save your money for something else. It really didn't do much. I heard they make big gains on the 996 and 997.1... but on my 997.2... no big difference. I'd spend maybe $200 on it... but not $1,000.

love2drive

Interestingly, while Sharkwerks does not explicitly recommend this in their advice section, they do offer it on their site.
I've heard that upgrading the Plenum on a 997.2 is not worth it from a lot of members. There's little gains to be had with the GTS.
I'd advise against the Plenum and if you want a change.. Sharkwerk's center muffler bypass which saves about 9lbs in the rear, and adds 12hp + 14ft-lbs while adding a significant yet not
overbearing amount of exhaust sound with a small loss in refinement.

I'm also considering EVOMSit Software upgrade which claims another 10hp & 10ft-lb although, $1K for 10hp/ft-lb seems more like a gimmick to me. Sharkwerks claims it makes the car drive better as well.
I don't doubt them, just not sure how woth it is to do this.

What I've found with my stock GTS is, using higher octane fuel > 93 always makes the car drive better.

NMSTT

Thanks for the feedback guys. Alex (SW) didn't explicitly recommend the IPD when I discussed my plans, so I assumed it wasn't a meaningful gain but wanted to see if someone had tried to put one on their GTS and could provide dyno (butt or roller) results. I picked up the tune and center muffler bypass from Sharky, have the BMC's coming. Maybe the IPD provides an incremental gain with other breathing parts changed but the flow increase wasn't recognized with stock parts in place, maybe there is something to be gained - but that's all baseless assumption on my part.

Fined

I wouldn't imagine that you'll get anything by changing the plenum on a GTS. same goes for the air filters. even with a tune you might get 10hp peak. Trying to discern 10 or 15hp in a car that makes 410 is going to be mostly placebo, I'd imagine. However, I do plan on getting a tune when I eventually do headers on the car, mostly for the CEL possibility. I might a few hp on the headers same as I probably got a few with the SW bypass. Even with SW bypass, tune, and headers.. I'm not expecting more than 20hp over stock. All that stuff is for the sound only.

NMSTT

I'll feel the difference, I have developed a sensitive feel for performance changes after 10+ modified German cars. The bottom line is that if the factory design leaves room for improvement, there will be gains. I guess what I'm looking for is less conjecture or assumptions about how tiny the gains may or may not be, rather some data or experience from those who have tried it.

vern1

You wont feel the difference regardless of how good you think your butt dyno is....

Have not seen anyone run dynos with just a plenum change except the manufacturers of course

In the best case of 15 hp its not going to make any real difference and in the worst case its zero. As Fined said, its placebo effect

But you wont believe us

sandwedge

What kind of headers are you thinking? Just curious since it's my understanding that the GTS comes with upgraded headers that are part of the X51 kit.

Fined

Thinking to go with cargraphic. Like these;

https://flat6motorsports.com/product...fold-set-997-2

It's as much about cats as it is the headers. Looking at the headers the GTS comes with, it sure looks like the ones I'm considering would flow better. Extremely unscientific analysis, I know. Just that the bends on the OE headers look more like "kinks" than they do bends. I'm not doing it necessarily to make power, more for sound. But if I'm changing parts there has to be improvement to the car function itself as well.

robgts

+1 on the x-pipe for the GTS...Great weight loss and it sounds great. Now...if I can just find $5000 in my couch to buy the Akrapovic full titanium exhaust

NMSTT

I'm also going with Cargraphic, only the catless variant. Since there seems to be a lack of hard data on mods, I'll use a performance tracker and video to tease out any gains or losses for each part change.

I'll take precautions like tracking ambient temp, always running with a full tank, and doing runs on the same stretch of pavement to eliminate as much guess work as possible. My car is PDK so the human error is limited.

It's counter intuitive to me that modifying power output is so fruitless when all the normal bottle necks that create power on other platforms exist with the GTS (too many mufflers, catalytic converters, intake air flow restrictions, conservative tuning for 91, etc). I don't expect it to compete with a GT3 RS, but how close to GT3 can I get it? If there are any Seattle based owners that want to accelerate along side me (for visual comparisons sake) I think the gains or losses could be better realized in comparison.

In the end I may prove that you all are right, and there is nothing to be gained but noise. Or maybe I'll add some value. Either way it should be a fun way to figure it out.

sandwedge

I have to agree. That OEM setup looks like a damn snakes nest compared to the Cargraphic design. At almost $3,300 I'll let you lead the way here though. Please report back with the results.