ScottArizona

I now have about 60 miles since completion of the 997 gt3 exhaust conversion on my car (oem 997 headers/cats, fabspeed side bypass pipes, oem 997.1 (steel) center exhaust, sharkwerks 80mm tips).

To say I'm stoked with the results would be an understatement. I was doing this primarily for the sound improvement and to lose a little weight off the rear (the hardest place to lose lbs). I had heard there is a performance advantage with this set up over the 996 gt3 set up, but I was honestly not expecting much, as literally every single exhaust I have ever put on an N/A car (multiple m3's, boxsters, a Carrera, a 997 gt3 (not to mention three different exhaust configurations on this very car), resulted primarily in a different sound, sometimes improved throttle response, but usually nothing noticeable in terms of performance increase (aside from the perceived increase in performance associated with an increase in exhaust volume!).

Well, I can honestly say that is not the case with the 997 conversion. The performance increase is real AND noticeable. Maybe it is that my old set up was not optimal (my mufflers were an unknown brand, so who knows if maybe they did not flow well), but I can honestly report that the car feels significantly quicker. And I know its not a "placebo" effect I'm reporting because the car now looses traction in spots/speeds/rpms where I know it NEVER lost traction before. Here are some other observations.

1) Throttle response: Definitely improved. No doubt. I have an rs lwfw, and this mod is the icing on the cake. Throttle inputs result in sharp and immediate rpm responses. I feel like I've added one of those spint booster thingies (which I've never tried LOL). Car just reacts quicker now, especially when blipping the throttle with no load (such as rev matching upon downshifting).

2) Sound: I think its perfect. Volume is not too much louder than my old set up (fabspeed headers and unknown brand titanium mufflers), but the new sound is much more crisp, exotic sounding, and deeper. There is drone in the 2500-2800ish rpm range, but its not bad and I don't spend much time in that range anyway.

3) Aesthetics: I'm 50/50 on this one. The car definitely looks more modern and racy with the center exit exhaust. I also like the deletion of the bumperettes...car just has a more muscular look now. But I don't like how much of the exhaust hardware is exposed under the cup bumper, which is cut much higher than the oem 996 and 997 gt3 bumpers. Its not horrible, and definitely looks the business, but I would prefer a little more refinement for my "street" track car! I also need to figure out a tow hook solution that retains the bumper reinforcement bar! The bumper is going to go back to get re-painted as there are some flaws, but at least the shop got the color match just about perfect.

Anyway, I can honestly say that if I could only pick one mod on this car out of all the other mods/options on this car (pccb's, euro perlon seats, rear bar, lwfw/clutch, bmc filter, 996 gt3 aftermarket headers and mufflers, etc...), this would be it. I'm that happy with it. Below are a couple pics.

NXI20

Cup bumper tow hook retaining rear crash bar

This is how I did mine

ScottArizona

Thanks for that pic. Interesting approach. While you retain the crash bar, with the way it is attached, you do lose the shock absorption function of the bar, since the bar is now mounted on the passenger side frame instead of onto the shock absorbing "protrusions" or whatever you want to call them!

Also, for the record, if you are going from a stock set up to this 997 set up, you will loose exactly 58lbs per my (probably inaccurate) bathroom scale. I only lost 37lbs though because I went from aftermarket mufflers/headers.

I should also note that I did a 3rd gear freeway roll with my buddy last night in his 997.2 gt3 with full bbi "street cup" treatment (lwfw and clutch, side bypass, cup bumpers, cup wing, tons of suspension mods, cup intake and filters, headers, etc....). We started in 3rd gear at about 4k rpm, and his car was no more than 1/2 car length ahead, and he got the jump. After that, he really couldn't pull away. I was impressed (so was he). From lower rpms his car feels quicker, but when the 996 is in the meat of its power band, with these mods the two cars were surprisingly close!

177mph

Great update and info. Very interesting

John@Fabspeed

Awesome build! Glad we could help be a part of it with our SMBP : )

DHI

Looks good!
Thank-you for sharing in such detail.
I have 996 cup car exhaust right now but this is a good option for sound level reasons or just plain replacement.

KOAN

I put a 997.2 Cup exhaust on last year. It saved quite a bit of weight, like 80 lbs. I dyno'ed it before and after. I gained about 5 hp in the midrange and lost 5 at the top ( compared to the Europipe that I had on previously. I think it is due to the short tube headers. The system has small cats. I can feel the difference in the weight, though, and it sounds pretty cool. I was hesitant to take it to NCM because they have a pretty strict 102.5 db policy, and I'm pretty sure, at WOT, I'd fail.

I put a bung on for the 2nd O2 sensor after the cat, and I've never had a CEL.

I'd do it again. I think a 4.0 R&P would be a bigger performance enhancement, but I have not done that yet. Matt also says that the power gained in the exhaust is in a better header and no cat.

cello

Nice info OP!

And thanks Chuck as I was wondering on dyno info pre and post.

I would love to see a thread on the 'hierarchy' of performance mods as I find myself somewhat "paralyzed by analysis"....

I would think re-gearing (as opposed to R&P) would give the most performance gains from stock, from my experience (w 997 gearing versus etc) but you guys know more than me on this (assuming the usual lwfw, shifter/cable mods already done)..

Maybe a new thread at some point by someone in the know?

AudiOn19s

This should be worth it for the sound alone. From the day I bought my GT3 I knew I needed to do something to change the sound of the 996 because I personally couldn't stand it.

Reminds me of top gear from last night if anyone watched it. Chris Harris raved and raved on the new Cayman but in the end couldn't stand the sounds of the new 4 cylinder turbo sounds coming from the exhaust. He said he'd drive the old 6 cylinder Cayman GTS long before he'd buy the new turbo car.

I felt the same way about the 996 and ended up having my own customer solution built but the development of being able to do 997 parts makes it really very easy to carry out and get the sound that these things should be making.

ScottArizona

This is really confusing to me. There is no way I lost hp with this mod. The difference is not subtle. And I'm not some fanboy looking to justify the time and expense of the mod post-hoc (I've modded every performance car I have ever owned, and trust me, I have been very underwhelmed by most). This is a really solid mod in my opinion.

Maybe its because you did the cup system. When I was looking into systems for my old 997.1 gt3, Rhonda at FVD strongly advised against the m&m cup-based 997.2 systems for the 997.1 as they felt the flow characteristics were not ideal for the 3.6l engine (too little backpressure). I didn't do a before/after dyno, but the seat of the pants difference is definitely noticeable, and this is consistent with the observations of several others I spoke with prior to embarking on this project, as well as the reports by members here who reported a 20-ish hp increase with this exact set up over stock on same day dyno runs.

Backmarker

All of this could be answered with a dyno chart- did you dyno before your mods and after like Chuck did and the others that you allude to?

Think it's important to have data to evaluate results as we are emotionally bought in to our cars and the mods we choose.

KOAN

Sorry, I can only report my own experience. There are many variables, including what each of us had on before ( bad cats?, stock vs. Europipe) and what we put on (cup vs GT3 vs 997).

I was at max 363 hp, 273 lb/ft at the wheels.

mmuller

Chuck, do you have a tune?

cgfen

Congrats on making a mod that you are very happy with.

Please remind us why you used a 997 Cup? rear bumper cover instead of a 997 GT3 (street) bumper cover.
Or is it a 996 Cup B/C?
Yes, I'm ignorant.

KOAN

No tune. 43k miles. 93 octane. Stock RP and gears. normal interior A/C, radio. You pull away from me so quickly it is embarrassing. Will you be at WG next weekend with ARPCA? I have a surprise...