Car is not completely finished but here is a preview. Final touch bodyshop did an exceptional job as always. Fabspeed catless sounded great without cel (so far), a bit too loud for extended drive topless but I can live with it as I don't d/d. Cobb stage 2 is another level of fast, however I'm still unable to drive it smoothly. Sport and sport plus mode is simply too much for street use and the rifle backfire noise scares the living &&&& out of others. More feedback to come.

 

Nice

 

She looks incredible. I have not detected a lack of smoothness issue with my GIAC stage 2 but will need to drive a Cobb Stage 2 car for a comparison. And yes any catless exhaust is loud especially in a cab with top down.

 

Also I assume that you are not getting the backfiring in normal/comfort. You get It in sport and especially sport plus due to different fuel mapping. I do get backfiring/popping with my Europipe but it is not as loud as catless due to EP's 100 cell cats.

 

That is correct sdg, although once in a while I get backfire too in normal when I accelerate really hard and let go the gas.

 

FYI, more gas in the cylinder to be dumped out means more to burn, which creates a louder noise.

 

Sdg wanna swap exhausts + cash?

I hope the system quiets down after breaking in. Although that backfire sound is something that makes me nervous, too much unwanted attention and not necessarily in a good way, more like wtf was that way.

Now on to the Cobb stage 2 ots 93 map, I only had 2-3 hours of seat time therefore my impressions are preliminary. I no longer feel the need to drive the car in sport or sport plus, I would like to, but the super aggressive throttle response and sound of backfire makes street use of these modes impractical. Like another customer had felt, the boost gauge goes to full when I'm about 1/8 th way into the the pedal. This is a strange feeling as you feel 80 percent of the power with maybe quarter of pedal travel and when you WOT, you only feel another 20 percent improvement. This could be due to the nature of the torque curve, I have no idea as I'm pretty new to turbos and engine modifications.
Also the car lurches around 3k rpm, I see the needle jumps when it hits around that range, I'm not sure if the car was shifting or the boost came on, but it's certainly not linear.

I will need to spend more time with the car and will provide review at a later time. Mitch is also writing me a custom map so I will have that on next week.

The software with this catless setup without a doubt yields significant power improvement over stock and stage 1. And I'm sure I will get used to the performance for street use over time with cobb's exceptional customer service and support.

 

my 200 cell cats are loud and very loud burbles in sport mode especially when hard on the throttle.


I can only imagine how enhanced that is catless.


but I will say I was same as you at first - very nervous about the sound and really didn't want the attention, etc. but as I've driven it for the past few weeks, I've gotten used to it and actually enjoy it now. so give it some time.


your review of the super aggressive throttle response is not at all my experience with the GIAC Stage 2. it's super smooth and very drivable, just like stock.


sounds like Cobb may have gone overboard with the early boost levels and made it like a muscle car.


sad to hear that.

 

Yes I hope I will get used to the backfire, I don't mind the burble but that single rifle pop is a bit too much.

Let me drive the car a little bit more before we draw conclusions on the driveability of cobb's tune. There are a few others with stage 2 and they seem to love theirs. Some people may like it more aggressive some may not. I will let sdg who has giac stage 2 to drive my car as well.

 

Thanks but I am good with my Europipe. It Has the perfect amount of noise for me. Not too much but not too little. You can hear the backfiring but it is not overwhelmingly loud. You can hear the turbos and the wastegate. I would only switch to catless if there is a significant performance disparity actually shown on the champion Dyno. If it's 10 or even 15 hp I'm keeping my Europipe. If it's 50 I might switch to catless but really don't want to. My understanding is that, unlike the 997.2 TT and TTS, there is not a mega difference between high flow cat performance and catless on the 991 TT and TTS. And if I were to go catless exhaust I would definitely go Tubi rather than Fabspeed.

Yours is the first report I have heard of an uneven or rough throttle response with the Cobb tune. I definitely have to drive your car to evaluate it myself. That I do not have on my GIAC tune. It is smooth and OEM like in its power delivery. Hopefully Mitch can give you a map with a smoother power delivery. Feel free to reach out to to me to drive my car once I get it back from Champion to see if the power delivery issue is in my car and I am just not feeling it. As you know I am not shy about being critical of problems that I detect with my mods as well as giving praise where I think they work. The only negative thing I experienced with my tune was tremendous heat soak at events. Other than that the operation of the car is fantastic and daily driving and highway driving is outstanding. And the heat soak did not disable the car or send it into some rough limp home mode a al BMS. The ECU just simply dialed back the boost and the timing a bit to keep those intake air temperatures in check due to the inadequate stock intercoolers. And even the dialing back was quite smooth and not rough in anyway. Just a slight slowing in the rate of acceleration. Hopefully with the intercoolers and revised tune that one problem will disappear.

 

When I'm in to 1/8th pedal travel, my boost gauge hardly moves. I'm on the Cobb Stage 2/93 tune. I do not find it overly aggressive, as one poster here has stated. It's very linear at all times, exactly like the OEM tune, but more power across most of the band. It does not change the pedal feel/ response dramatically either. I have no idea why JYUPITT1 has this issue, I don't and have not seen anyone else with the Cobb tune post anything like that either.

No question that with the cats removed, it will be noisy as hell, drone more, and pop very loudly on decel. I chose not to remove mine, but change them for high flow instead.

My mods are:

Techart
Fabspeed headers/ exhaust
BMC intake
IPD Plenum
Cobb Stage 2/ 93
Wheels and tires

 

It's good to have confirmation that others don't feel the same way as me. I'm sure it will get sorted maybe I just need to know how to drive ! : D However there was one poster who had similar experience with the short pedal travel and full boost mode.

 

Depending on who you purchased the tune AP3 from, they may offer a data logging service included as part of your purchase. I got mine from a vendor here who will review my logs and make the modifications needed to tune my particular vehicle. I haven't found the need as of yet, but will eventually do it.

Something else you could try, which or may not do anything, but is certainly worth the effort, would be to unload the tune, drive it a bit and run it through the gears. Feel how it drives stock with those mods, then reload the tune and run it again to see how it drives tuned. It may not react the way you expect, modded without the tune.

It may give you a good idea as to where the exact issue is...if it's a tune issue at all. It's worth a shot and takes only a few minute to do yourself. I think I loaded my tune in about 7-8 minutes from start to finish IIRC.

 

Thanks SRT, I plan to do that all that and more.
Here are my thinking for the non linear "feel"
1) exhaust sound- it makes all kinds of different noises at different Rpms and pedal pressures. Some are bassy where I can feel the metal below my feet vibrate and some are high pitched. This makes "think" that the engine is doing very different things therefore it's not "linear"

2) Build up boost early with low pedal travel. This one without a doubt is a fact. I monitor the boost gauge and if I push the pedal in to about 1/8th, maybe 1/4th and stay there. the boost meter is at full capacity and when I WOT At that point, the car doesn't feel like it can generate much more power as its already at full boost. This gives the a car a nonlinear feeling.

3) car lurches around 3k rpm - I need to investigate further, I think this might the PDK shifting into a new gear. I need to observe further. Imagine your foot is down on the pedal lightly, you see the boost coming up in a fashion that is mentioned above. Then you watch the rpm raise to about 3k, (again same pressure on the pedal) the engine speed jumps very quickly then it continues to raise linearly.

 

I definitely need to drive your car to get a feel for what's going on as compared to what mine feels like. That doesn't sound like my experience at all but I don't really know until I see for myself