Calling Those Running Catless Downpipes

[domino_z]

Hi guys

Just put my 90mm ti exhaust on and running an 80mm ss milltek non-res midpipe with oem cats

The exhaust didnt really add much to the sound i was getting from the midpipe only - if anything its only increased the volume slightly which was somewhat expected given it's an identical layout to the oem setup

So now im thinking of jumping in the deep end with catless dp's and perhaps playing it safe with a resonator'd 90mm ti midpipe to take the edge off

For those running catless dp's, and im pretty sure there's a good handful of you now, how loud is it now that you've lived with the car

Is there any boom or resonance coming in through the transmission tunnel or nvh at certain rpms? Can you tell you're running catless when idle'ing or in auto mode shifting below 2k?

And lastly, are you getting a build up of carbon on the rear bumper?

I found this vid on the tube and like the sound, but it's hard to tell how loud it is inside the cabin

Edited June 10, 2011 by domino_z

[jjman]

goddam that shit is full tilt car porn. *like*

[kymbo]

If you want the big angry sound, more flow and performance you do NOT have to go without cats.

Most R35's are fitting 3" catless dumps.

Mercury Motorsport made me a set of 3.5" catted dumps with very big high flow cat bricks.

When you look through the cat, you are looking clean through the brick to the other side.

The Dyno has proven they flow the same and maybe slightly more than the 3" catless dumps.

Not to mention it is nice to have your cake (power & sound) and able to eat it too (CLEAN EXHAUST & LEGAL).

The 3.5" catted dumps with my full Willal Racing Titanium exhaust system sound awesome.

The in cabin noise does get very noticable, however by wrapping the entire system with Titanium tape the NVH cabin noise noticeably dropped off. I use the car as my daily driver and find the in cabin noise OK.

I also recommend a competition air intake system (Like AAM System), big jump in power and a really cool growly induction noise with an audible turbo shrill.

[domino_z]

thanks for the feedback mate, ill look into hfc downpipes

my midpipe is 3" at the downpipe so would go with aam's hfc downpipes

i have the full Top Secret intake and turbo inlet pipes - installing them over the weekend

Edited June 10, 2011 by domino_z

[domino_z]

Finally found a vid with hfc downpipes and it's not the raspy sound I'm after

So will to straight downpipes and swap out my midpipe with the Cobb catted

[domino_z]

Hmmmm pretty much every tuner is telling me to avoid using metallic high flow cats in the downpipe because they fail easily with high heat

[Godcla]

Is there anyone that can give me some help/advice on cutting the cats out of a set of std Downpipes.....

[domino_z]

much easier to buy catless downpipes

[Godcla]

much easier to buy catless downpipes

I have a set...but would like to have a go with a set of std ones as I reckon they will never crack .......I'm a DIY Guy...what can I say.

[EuroDB]

Fine information, many thanks to the author. It is puzzling to me now, but in general, the usefulness and significance is overwhelming. Very much thanks again and best of luck!