I now have a 3" secondary cat bypass, midpipe, and muffler from HHR. My question is how much louder will my CTTS be if I get a high flow primary cat or a primary cat delete? Will it be too loud to be a daily driver? Does the performance justify the increased sound? If I continue to modify my Cayenne, will the stock primary cats limit what I can do? I am wanting to decide before I get a tune so I don't tune it twice quickly. Thanks for anyone's experience

 

Well I still have my primary cats and I'm not an expert. But I'd say if you are willing to spend the money for the sport cats go that route. I think you'll get close to the same performance but with slightly less sound and less stink. Although I'll admit I'm getting used to the stink of a modern car, t's just not the same as my old carbureted 308 with a very open exhaust but I'm growing to like it.

 

jdubbya - do you think there is much difference in the sport cats vs the bypass? A little less sound and 3 times the price. I saw were Fabspeed said their sport cat flows 75% of a bypass. Not bad and they said that they could customize a 3" sport cat, but the person couldn't get me a price at that time.

 

I've actually heard even higher numbers claimed for some "high flow" cats. I doubt there is much performance difference since flow is going to be pretty close. But yeah there is a huge cost difference. I have secondary bypass pipes on my 955. I paid for hig flow cats when I had the 308 but it was a waste of money because they run really rich and just ended up burning up the element within a year or two.


Like I've mentioned before, I still have my primary cats but I did talk to Kent who has a totally open exhaust and he said he didn't think it smelled much. If you don't have to pass smog I'd say go with the bypass. If it's too loud you can always add a resonator back inline somewhere in the exhaust.


I haven't heard a turbo Cayenne that was too loud yet though. I think the turbos quiet things down some. But that's me.

 

I'm decatted and the rear end was also degutted (all fiber out of the exhaust tank) plus i also have the secondary cat bypass and the result its pretty loud and sounds as it should. I don't have a GoPro to film this correctly but as soon as i'm done with my Techart Magnum mod and KESSY installation i can upload some videos for sure.

 

Bryan,

The primary sport cats would be a great upgrade and wouldn't push you into the "too aggressive" zone. You're cutting down to 200 cell cats from 600-800 stock cats so you can see where the gains are made. You can expect about 15 hp and an 18 lb weight savings over all.

Please let me know if you have any questions, I'd be happy to assist a fellow forum member!

 

I went with Hanks turbo back 3". He didn't have tips so I picked up some 3" tips and made it work.

 

That sounds so much better than mine. Makes me want to pull the trigger on the whole set up but it's not in the cards just yet. I did buy parts to install CAI on the front end though. And I have a 3 day weekend to maybe get it all done. Woohoo.

 

BG305 - you have the Hanksville primary cat bypass, secondary cat bypass, midpipe, and muffler? It sound good in the video. Is it too loud in person? Did you get the Softronic tune after the exhaust? Did they tune for the primary cat bypass? I have been talking with EVOMS and they only have a tune that considers the sport cats, not a 3" bypass. I was also warned that 3" all the way out could cause drivability problems with so little back pressure at the turbos. Do you have any trouble with the turbos having boost oscillations?

 

Yes, I have 3" from the turbos back. I also found 3" tips and cut the 2.5" outlets Hank sent on the muffler. So I am 3" all the way and cat free. The turbos are free to spool and I noticed it right away. I might have a video with the OEM tips when I first fitted hanks.

Is it to loud in person? I don't think so.

Softronic tune after exhaust? No, I did everything at the same time. I will say that I am not pleased with the tune. At WOT from a slow roll it goes to lean when it loads up.

Did they tune for the cat delet? I don't think so.

EVOMS - I also spoke with them about getting a proper tune and going with there intakes. This will probably be the route I take when I have some more time in Costa Rica.

Problems with boost? The only problems are on the load up once I get the turbos spooling it pegs the the boost needle then drops to .8-1 bar.

Drivability issues? None, drives great.

 

This is what it would sound like with the OEM tips.

 

I also went this route when the OEM started leaking.

 

Looks good and sounds good. Now you have me leaning towards the 3" primary bypass again. I am having a hard time finding anyone to do more than the EVOMS big turbo kit which they have updated and is not shown correctly on their website. I am wondering if there is another upgrade/mod with larger turbos and other mods, whether they would change the turbo location thus needing a different cat/bypass. It seems that until I am ready to have the motor built, that it does not make sense to do much more. If around 700 hp is the max reliable power and right now with a tune I should be over 600 hp, then I guess I will wait until I find someone with a plan for a bigger mod.

Any ideas?

 

Yeah I have an idea. All you need to do is check out The Renaissance Mans build on here. His CTTS is in the 800hp club.

 

Innkeeper here is the thread. I am still taken back at what Ken accomplished at home.

https://www.6speedonline.com/forums/...hp-808-tq.html