The pipes left that way for one reason, it was all the space available to for around the tiptronic transmission. On a manual you can get 2.5 inch piping down there but on the tip, stock piping barely fits. It sucks but that's why. On a top, filters on turbo or filters in fender wells is your only options.

here is a big though for example of how bad they are. This is comparing to a small k16 billet wheel (47.5/66mm)

 

Congrats on the times, fast for sure!


Filters on the turbos or fender well intakes are the way to go. Made a huge difference for sure on my car with stock k16s and SRM K2471

 

Nice times. The auto rocks for drag. Reminds me of when I owned a 99 Z28 Camaro with a high stall torque converter and I raced against manual cars that were all over the place at the track.

 

I think the soft tubing solution with the stock airbox for sub 700 hp is the best bet. Those K&N types just don't filter as well as a great big paper filter.

 

It gains at least 1mph without the driveshaft. Every bit helps when we're splitting hairs.

NT01 Sizes are 235/40R18 front and 315/30R18 rear. I run those sizes in AWD as well.

 

Yea, i've thought about going catless but the drone with this Tiptronic is already pretty loud. I'd have to get some anti-drone pipes welded in first. Unfortunately the Tiptronic also limits the size of intake piping I can use, so I felt going this route was going to be the simplest, i'll just stay on top of the filter/outerwear maintenance.

These runs were on MS109. Based on my previous pump/ms109 setup, there's about a 3/10ths difference between the two fuels/tunes in the 1/4mi. I'm guessing it'll run 11.3x on pump 93 octane.

Thanks!

 

Don't bother with Catless, John's 100 cell race cats flow awesome. PowdrHound has a thread about cats and power and he found zero benefit to catless setups vs. good race cats.

 

Pls read the DETAILS in his post as that is not a blanket statement PowdrHound makes:


https://www.6speedonline.com/forums/...e-settled.html


He is using the best 5" cats from HJS that cost over $2000, which is 70% of the cost of what these complete exhaust systems are selling for.


Here is just one quote of many in his post that shows his specific test with one of the most expensive and the 2nd largest cats HJS sells is for PowdrHound particular cats in this particular test and not a generic blanket "no difference between $400 3" 100cpi vs $2000 5" 100cpi vs catless:


Quote:


"Let me caveat this by saying that NOT all cats are the same even when comparing 100CPI cats from the same manufacturer. Most people do not understand this simple fact but you can just look at the HJS website and see all their various offerings of 100 cell Motorsport cats with various ratings from Cup catalysts, UL (ultralite) catalysts, or the top the line PE high flow catalysts. Sizes available are from 93mm diameter all the way to 153mm diameter and prices from $400 to in excess of $1000 per core. Hp rating for the various cores range from 360hp/pair all the way to 900hp/pair on the large diameter versions. " PowdrHound


When I had the 996T I had the Speedtech 3" with 100cpi cats and then did catless. Let me share with you the difference in spool, power, sound and drone was night and day and all for the best. I had to get EPL to retune my car as I went from 1.3 Bar to over 1.5 BAR after the de-cat only and had to get Tony to lower my boost back to 1.3 (Billet K16). The car spooled sooner, made more power. had less drone & sounded off the charts with the turbo whine/high end shriek and all the burbles and pops


Concerning Drone:


The car sounded so much better and the drone decreased as the sound must "bounce" around more in the "cat" chamber. I had a long discussion with John at Speedtech regarding this & he assured me that was the case with cat-less you get less drone on his system, but db levels go up. Hence when I did my 997T, I called John at Speedtech multiple times & I went straight catless and mufflerless & drone is minimum, but the overall volume of exhaust is at a louder DB level that's all. I wanted the most exotic sounding 911 and I got that with less drone then the minimal I got from my 996T Catted and mufflered 3" Speedtech....got my cake and ate it too.


Hope the above helps!

 

I have read the details of that thread. The SpeedTech 100cpi cats are NOT $400 3in cats. While they are not as big as those HJC cats, they are $1200 4in 100cpi cats. Which give a void area close to a 3in bypass pipe.

Do you have back to back dynos with and without the cats to back up your claims? Are the cats that were available from speedtech back then the same as the custom ones they have now?

 

The size of the HJC cats is why they flow as well as they do...

 

Interesting information about the cats vs catless. I may pick up a set of test pipes for comparison sake.

Thanks for the input fellas

 

I know. I'm pretty sure my last post covered that. The SpeedTech cats aren't tiny.

 

your running the top plastic right? if not thats BIG BIG NO NO

 

I posted on top a mph without cats on a switzer exhaust, same MPH... and even on a 93 octane.... I doubt you will gain anything...
now, add a 1 bar wg and a 5 bar fpr, it may help...

 

They're at least 20% smaller diameter than the HJC cats... the HJCs are at least 5", maybe 5.5", where as the SpeedTechs are 4"... not apples to apples.