I decided the budget allows for adding another dose of performance to the CTTS, and I'm trying to decide between either installing hi-flow primary cats (bypass pipes not possible in my EPA Gulag) or an ECU tune. Already have secondary bypass pipes in place and a few other upgrade goodies. Anyone have experience with the hi-flow primaries? How difficult as a DIY install? Recommendations on a good CTTS tune?

 

There is a review for CTTS on Softronic Tune.

https://www.6speedonline.com/forums/...lled-ctts.html

I just placed an order for my CTT and will provide feedback.

I'm afraid the hi-flow primary cats will make the car too loud with secondary bypass.

 

A good tune will net you 50 wheel horsepower in the $1,000-$2,000 dollar range, while a set of primary cats will be around $2,000+ and yield 10-15 wheel horsepower. We always recommend the GIAC tune, as they are one of the only companies that actually rewrite the factory code, but you will definitely still see gains by going with a cheaper option.

 

I'm almost thinking mine is too loud already with the bypass pipes and its Tubi exhaust. What's a few more dB's with hi-flow primaries?

 

Well... my hi-flow cats on 997S were very loud at WOT with a OE sport muffler. I liked it on the Carrera, but I wouldn't like it on the Cayenne. The turbos may muffle the noise, I just don't know by how much. I don't want my CTT to sound like an American truck with a straight pipes.

 

Checked their website; they don't offer a tune for the 955 Cayenne Turbo S (but they have tunes for the later 957 and 958 Turbo S models).

 

Agreed, my lovely wife is already "suggesting" I re-install the stock muffler. Maybe the hi-flow cats, bypass pipes, and stock muffler might be the perfect combo for achieving the best sound and power.


What I'm struggling with is why the huge differences in prices for the primaries. You have AR Design around $1,600, Fabspeed at $2,300, and premium German versions (e.g., Cargraphic and FVD) at about $3,500. Surely there can't be that much difference in quality, fit and performance between the most and least expensive?

 

Trust me, it will not sound like an American 1/2 ton pickup with straight pipes.

 

Yes, GIAC does offer a tune for the 955 Cayenne Turbo. Retail price is $2,000 and power gains are 50 wheel horsepower and 60 wheel torque on pump gas (with no other modifications).

 

Read carefully: Turbo S, not Turbo. A Turbo S tune for the 955 is not shown on GIAC's website. But thanks anyway.

 

The website is not always up to date, but GIAC does make a flash specifically for the Turbo S. The ECU is the same, it just has modified factory programming. Most users will opt for downpipes with the flash, since the power gains from flash alone are not as high as the non-S model.

 

It is - you will like it. Even better with NO cats and you shouldn't have a problem passing any testing with the correct ECU calibration. You could always "get to know" someone at the testing facility.

 

spooltime....this ^^ is correct. There is a tune specifically for the Turbo S available. We have flashed quite a few of them in fact. But as ED mentioned, since the gains are not quite as high as flashing a standard Turbo, most people opt for downpipes or high flow cats along with the tune to give it a little extra bump. If you have specific questions, feel free to let me know.

 

My review of the softronic tune is linked above in one of the first posts.
I would very strongly recommend it. It too rewrites the whole ECU & is only $1395 with a durametric cable included as a bonus.
If you already have a Durametric cable & don't need one, they will give you a $100 discount with a code at checkout so that reduces the cost to $1295.
You would be hard pressed to add 60hp any other way for that $$ on a stock CTTS.

 

It actually is only re-writing the factory maps. Re-writing the whole ECU involves writing proprietary ECU code. This is one of the reasons that GIAC is able to offer on the fly file switching.