05 CTT 75kmi completely stock

i just ordered Softronics tune, what other mods are recommended to go with the ECU flash? thanks in advance

 

Secondary cat bypasses should be next on your list. They will help the turbos spool a bit faster and help power while also giving you a bit more aural pleasure

I would also replace your diverter valves with upgraded units to cope with the increased boost pressure. This is a reliability mod.

The other things you can do like the rest of the exhaust and intakes are mostly just sound upgrades. They may increase power a bit, but it's nearly negligible.

 

Like it was mentioned, upgraded diverter valves, intakes and secondary cat bypass.

 

What brand diverter valve is recommended? Thanks for the replies

 

There isn't much difference. There are two basic styles - the billet aluminum version with an aluminum piston like the EVOMS, Forge, and Agency Power. Then there is the upgraded diaphragm style, like APR sells- which is allegedly faster responding.

FWIW, I am running one of the former billet styles.

 

Thanks for the advice just ordered a set from apr

 

I prolly won't do the 2nd cat bypass for now, but if I do what is the best bang for buck brand? Thanks again

 

Doesn't matter; it is just straight SS pipe. Get whatever you can, that also has 2 hangers. Also look for a used set if you are not in a hurry.

 

Steven,

I think you made a good choice on the diverter valve. The problem with the piston type valves is that they need to be serviced (greased) occasionally. They WILL seize up over time if this is not done. The diverter valves on these Cayennes are not particularly easy to get to, so going to a strong diaphragm-based valve is the smart move in my opinion. Otherwise, I'd go with a piston type as they will never wear out as long as they are serviced regularly.

As far as the cay bypasses are concerned, the best deal out there for new ones is the former Leistung pipes. The manufacturing of these pipes is now handled by Hanksville Hot Rods (hhrproducts.com). They have had three (I believe) revisions due to hanger problems, etc. and now have a really nice hanger setup.

Fabspeed makes nice ones, but they are up there in price.

I decided to go with bypass pipes by BillyBoat exhaust. The reason I went with them over the Leistung/Hanksville units is because they also come with midpipes, the pipes between the cay bypasses and the mufflers. You can get them for around $525 with free shipping at LM Performance. I've heard mixed reviews about this company and it's quality, ownership, customer service, etc., but I'm taking my chances. The hanger rods on these look nice and thick too, so they should hold up nicely compared to the OLD Leistung pipes which had problems with the hangers breaking.

 

goods and bad news
good news got ecu back and car was boosting hard
bad news after boosting hard i think a hose popped off or split
the car makes a slight suction noise when i let off gas pedal and idles super rough
this should be fun

 

Check the lower and upper intercooler hoses. Also, you should have changed your diverter valves at the same time to make sure you didnt tear the stock DV diaphragm with the higher boost levels.

The boost is higher than stock, but not a level where you should be popping boost hoses (unless already loose). I think stock boost is around 12 psi and the tune should put you around 15 psi. Not alarming boost levels.

 

That's definitely a sign of a big vacuum leak. I'd put my money on diverter valve too if it isn't obvious that a hose pops off after a cursory look in the engine bay.