987 sound insulation

The background: My new to me last year, 2009 CS has 141k on it. We are planning a long road trip this summer (STL to San Fran and back). On a shorter trip the spousal unit told me the cabin was too noisy on the interstate for a long drive. Since I was taking out the driver seat anyway to get it refurbished (which went awesome), I decided to pull all the carpet at the same time and install sound deadener. Since I was going to have the doors apart anyway, I did speaker replacements at the same time. The results: My wife says its quieter. Period. I say its slightly quieter, but mostly the high pitch aggravating sounds are reduced or converted to lower pitches that don't bother the ears as much. I can still hear the engine, though not every little tick like I could before. I can still hear the sweet, sweet exhaust note. It still has road noise. It's still the noisiest 4-wheel vehicle we own. Sound deadening the doors and floors did nothing for the wind noise around the window seals. New speakers sound amazing compared to blow out originals. The purchases: NVX SDDK12 - 12 sq ft - $43 Noico Red 150mil 36 sq ft - $54 Focal ISS-200 8" 80 watt RMS 2-way - $270 Focal ISN-4 Shallow 4" 40 watt RMS mid - $170 installation rollers - $14 Total: $551 The plan (high level): - sound dampening material - Metal parts amplify sound and become cymbals. This reduces that action. You don't need 100% coverage for this. I went for 15-20% coverage. The internet says 20%. Sellers say 100% because they want to sell you more. - sound insulation material - this takes the sound coming in and absorbs some of it. Anywhere you don't have this is a place sound is going to travel through better. I went for 90%+ coverage on the places i thought the most sound would come through. Specifically facing the outside world. Given the above, I didn't cover the wall shared with the frunk or the center console, but I did cover about everything else with insulation. I don't know about your 987, but under both seats on mine was bare metal. No carpet, no insulation, nothing. I put sound dampener here covered by multiple layers of insulation to make up for the lack of factory insulation. The carpet actually has pretty thick insulation on it. I suspect a lot of my noise came from the empty holes under the seat. The detailed process: See first comment.

The detailed process: (thanks @ruslanvideofilms for some of these great howtos I linked below) Disconnect battery. Remove the seats - 4 bolts each, unhook wiring. Easy. Unbolt the amp (if you have it) under the passenger seat. My RCU was loose already. I just flipped them up out of the way while installing insulation. Remove the center console. Remove the carpet and insulation behind the seats. I don't have a good video for this. I highly recommend removing the bar first. Its only 2 little trim piece and 2 bolts and it makes the job easier. Remove the lower door trim. Passenger side is just a trim screw down in the middle. Unbolt the seat belts down by the floor inside the door. 17mm. Pull up the carpet. There are some other places where the carpet might be a little tricky or you might need to remove more trim. I didn't take good pictures of this, and I didn't find a video. But I didn't find it very difficult either. The trickiest thing with the carpet was getting it to fold enough to make it under the steering wheel as I foled it to the other side. I removed the dead pedal but not the bracket underneath. This caused me some trouble. More later. I also disconnected the gas pedal (bolt near the top, hook at the bottom. This made it easier to get insulation where I wanted it. Sweep everything. Sweep again. Scrap if needed. Sweep again. Clean everything with a wet rag. Rinse it often. Dry it all off and let it sit and dry for a few hours. Use isopropyl alchohol on a rag and clean everything. Do it twice. Clean surfaces are key for good adhesion. Install sound dampener. This is pretty easy. I tapped around with the butt of the roller to find places that were noisier. Larger panels make larger amplifiers so I focused there. You can cut the dampener with scissors. The scissors will clog, but can be cleaned pretty easy. I found the 0.6" roller worked best for almost everything. I paid special attention to the edges where they will start to peel first. Install sound insulation. WEAR GLOVES. This stuff is crazy sticky and will get all over your hands. Do not roller. Sometimes I used cardboard to make a pattern. Sometimes I just stuffed it in place, drew on it with a sharpie, pulled it out and cut it. Cuts easy with scissors again, though I did keep a utility knife handy. I did a rough layout of pieces first to come up with a general plan, but waited to cut until each piece was going in. I came back and doubled up in the well under the seats. To install, I would pick a starting side, pull the paper down just a little and fold it over, hold onto the paper covered area, line it up, and start sticking. The moment it touches the metal it will stick and not come loose without ripping, so be careful. You can stretch it a bit and make it conform to contours, as long as you hold onto the paper covered section and not the sticky section. Once the starting side is down, grab the folded paper and start pulling it out from underneath as you guide the mat into place. If you grab the sticky section, you now have insulation on your gloves. See all this nice foam on the floor blocking sound? Its great, but that dead pedal cover I talked about earlier, when I went to put it back, it wouldn't go all the way down because there was too much insulation in the way. It has grippers on the back that grab the carpet. I thought I was going to have to live with it loose. However, after stomping my foot on it hard while driving a fun road, I found it also had a clip and stomping it with my foot got it all the way back down where it should be and its nice and solid now. YMMV. Put the carpet back on that side, repeat on the other side. I am slightly concerned about the amp. It barely fits on the posts and is hard against the insulation now. I worry about heat. Though it still has plenty of airflow on top. Insulate around the engine bay. Same process. I had a lot of sound deadener left, so I was more judicious with it. Dismantle the doors. There are dozens of videos on this. Pick your favorite. As with under the carpet, clean, clean, clean more. The doors are extra dirty inside. The doors already have sound deadener in them from the factory. I added more. I also put a bit of sound deadener on the outside of the middle door panel. I hope that makes sense. It will when you have it apart. And then put insulation in the door on the inside of the outside panel. I was beat at this point and completely forgot to get pics of the doors with insulation inside them. It looks a lot like the floor, except I didn't go over the brace. I tried to stuff the sticky mat down behind the brace, though that didn't always go great either. And then replace speakers. See @foodbiker 's excellent thread for more on this. I have pics, but I don't think they add much. Put the doors back together. Repeat for the firewall behind the seats. At this point, put it all back together. I did test the speakers repeatedly before fully assembling the doors, but I did not test ride the insulation before putting the center console and seats back in. I figured it was either better, or it wasn't. My wife approves of the quieter ride!

Nice job, and clearly a lot of effort! If you had to replace this car with another 987 for whatever reason, would go through all that again? I’m on the fence about doing some of this. I had a 4 hour road trip a few weeks back, and while doable, the ears were definitely tired at the end. I’ve also heard that insulating the wheel wells behind the fender liners is an effective way of reducing road/tire noise, but can not confirm.

What an absolutely fantastic and thorough @wwexell DIY! WOW. Great job. Although I did the doors two years back (thanks for the complement!), I have yet to do the rest of the car. Sure enough, I inherited a half-used box of Kilmat from a friend and have yet to do the rest of the car. Unfortunately, I'm distracted with other projects but this one is up there. Yes, it's bare metal under the carpet. Having sound proofed a few exposed areas of the removable hardtop, it knocked down some of the road noise but what you did is clearly the way to go. I'd like to eliminate tire noise if possible and hopefully this helps. Methinks the lack of insulation involves a balance between lower weight (fuel economy, performance) and costs. I finished restoring my folks' 2002 Mercedes S500 last year, and wow - the amount of padding was significant. Then again, that's a luxury 4-banger than a sporty roadster. Let us know your longer-term impressions on this. Again, great job!!!

Yes, after driving the car and seeing if it sounded like my current car did, yes I would do it again, though I would hope it didn't need quite as many other things while I was at it. It seems like a lot, but it really wasn't that bad. It probably went faster because I've already had the door apart multiple times for other things and knew exactly where to go with it. The interior stuff really wasn't too bad. The insulation took some getting used to, but then went rather quickly. I've heard that too, and I'm missing plastics in my front wheel wells. Fixing that and adding insulation would probably also make a difference.

Thank you! The bottom of the carpet in my 987.2 actually had good insulation I thought... just not everywhere it needed to be. I completely agree that there are weight savings to be gained by having less insulation, and everyone wants these to be light cars, which is why P goes that way. There is a reason the hardcore sound deadening sites recommend goals rated in lbs-per-sq-ft. I actually sent a pic of the bare floor to a racing friend and he was encouraging me to go the opposite direction.

Agreed, @wwexell - If I was severely stripping out his 987.2 for track-use only, sure -- I'd forgo the extra weight by skipping extra insulation. But as my 987.2 is my DD and touring car, that I already suffer from tinnitus, and as our 987s are pretty loud, a quieter cabin would be welcome. BTW - I'm assuming you were easily able to remove the front of the carpet once the pedals were removed? I know there's as velcro strap that threads under the dash from the driver's to the passenger's side. That was a bugaboo for me when I first got the car, and never got that far -- and am not looking forward to that part of the install.

With the gas pedal and the dead pedal removed and the lower door trim pulled (all pretty simple) and the center console removed (more difficult, but not awful), the carpet on the driver side came up really easy. I didn't notice the velcro till I was putting it back together, so it must have been loose already. If you've removed the center console, you've also taken off the side panels on the HVAC/stereo stack, and the velcro becomes fairly straightforward to access. On the passenger side, my carpet was glued to the right wall. Not sure if that was factory of PO, but it pulled off pretty easy. I didn't re-glue it. It seems to be staying in place well. If it starts slouching, I can glue that without really taking much else apart.

I’ll confess I didn’t read every single post but was curious if you tried replacing the window seals/weather stripping? New supple rubber may help seal some.

Not yet, but definitely considering it. I'm definitely getting wind noise around the seals.

I was curious if you had a chance to do the seals, if so did it help?

No. I have other projects that I need to get done. If I do that, it won't be till winter or next year.

for the wind noise, adding a thin layer of rubber striping around the door frame - that mirrors the rubber on the door helps. makes the doors a bit harder to shut though.

hey guys, remember it is a sports car... the definition of a sports car is "A car that doesn't have anything on it that doesn't make it go faster" hence the lack of insulation, which we all know is HEAVY, that is how it works. If you want to know how to insulate your Porsche properly then go look at the video about how Singer make their cars, they hired a guy whose profession is insulating executive jets, he went over every inch of the car with sensitive microphones analyzing where the sounds came from. Me, I just installed better speakers for the stereo & a big amp, turn it up!

Thankfully we all get to have our own opinions and do what we want to our own cars. The middle of July we took a 2 week trip from St Louis to San Francisco and back in my CS. The sound insulation definitely made a huge difference. I definitely feel like it made the ride more comfortable on the interstate. On the fun roads (like 89 south of Prescott AZ) the added weight wasn't noticeable at all, especially given the suitcases in the frunk and cooler in the hatch. Where it didn't help was some of the roads in the southwest, especially TX and NM. I swear they use 2" gravel in the asphalt down there. Holy heck those were some loud roads.