I liked mine, torque improved without question from mid end off the line. It's a very fun mod. RSS installed it without charging me and said if I didn't like it, they'd pull it off, guess that's how much they believed in it.

 

I have some very specific results to offer to the discussion.
Dynoed on a Maha dyno before and right after on my 997.1 supercharged Carrera 4s.
Installed 82mm throttle body AND 82mm IPD plenum at the same time.
+16 crank horses.
Is it worth the money ?
Well, it depends. If you are looking to maximize the output, yes.
But if it is the only mod on the car, NO.
Other mods are far more important for the money.

Just my 0.02

George

 

1k for 5% more seems like a lot.
At the crank or the wheels?
I think I'll just diet and lose 20 lbs instead :0)

 

If the question is for me, the answer, as stated is crank. Maha dynos
measure crank horsepower ( the most accurate dyno in the world ).
Considering that my car is supecharged, it is not even 5%. It is 3%.

 

Forced induction results not directly transferable to non fi motor. Need cats, exhaust and chip to get the most out of plenum in that case. Is it worth it? It is a way of making your car yours, ie personalizing it. I,d rather spend the money on a plenum and get that plastic pos out of my engine bay than put on a GT3 bumper or somesuch thing. Nobody asks a guy who spends xxx$ to bling up the exterior if it is worth it. To each his own.

 

since my next mod will be to apply a softronic tune, i'd like to hear your impression of your car after the exhaust, filter and softronic tune. thx.

 

Fwiw, you need to be cautious about the ecu mods. as you know from pushing the sport button it is real easy to remap the throttle and change the butt meter characteristics. Sport overdoes it imo. A good remap can make driving more fun though, and thats the point. So...have fun

 

Actually I did install an IPD plenum (with cats, headers, flash and intake) on my 997, so I speak from action, adn I'm not afraid to say I think I made a poor decision.

All I'm saying is neither you nor I have a good basis for saying the torque curve moves (or doesn't move), meaningful hp is created or not created), etc. because there aren't independent tests out there from unbiased sources (i.e., tests conducted by someone who doesn't sell the plenum or just shelled out $$ for it).

More generally, I think some of these performance mods probably make the advertised power, but it's not helping the industry's credibility when guys sell air intakes without heat shields advertised to make 18hp. In any business this unregulated, there will always be snake oil for sale.

If the manufacturers really stood behind their claims, they would arrange for independent testing -- it's not that hard to do and if results comes out like you are guessing, believe me I'd be the first to buy a plenum for my 991.

If one of the mod manufacturers wants to step up and explain why they don't submit to independent testing, I'm all ears.

 

I hear you. In my experience though the dyno has a hard time giving a valid and reliable number esp where reliable means a result that can be replicated over time. Most aftrmarket manufacturers do in fact give their own claimed hp increases. They can be hard to replicate reliably on a different machine under different circumstances. Then there is the issue of ecu adaptation which requires a period of post mod running time for the engine system to adapt to the changes. You can't just plug something in and retest. The engine and ambient temps affect the results. Looking for 25 horsepower on a dyno is not easy. A ll I can say for sure is that my car sounds different, feels different and has better throttle response and midrange than it did before. P max may not be that much greater but the hp under the curve seems more accessible if you know what I mean. I smile more. What can I tell you? It's worth it to me. For your 991: I get the sense that the earlier motors are easier for the aftermarket guys to play with. And if you rewrite the ecu you have to consider your warranty. Older cars can be more fun in some ways but it's all good.

 

At the time I had my IPD Plenum installed, I already had 200 cell cats and iPE valvetronic mufflers installed. Also at he time installed the plenum, I also installed racing headers. After installing the plenum and headers, my car really felt livelier. The car actually feels lighter and much more enjoyable especially in sport mode. Was it the plenum, the headers or the combination of everything? I don't know, but am happy with it!

I say plenum! Just change the one thing and report back!