Exhaust advice. Twin box? Trying to keep the sound down. Traders Welcome to chip in.

I currently have a cat-back custom stainless exhaust, I love the sound but its a tad quiet, I have been thinking about changing it for something that looks a little better, and has a slightly deeper sound.

It looks like I have just secured a mines NA5 ECU and apparently they are designed for a full de-catted system. Now I have a De-cat for the mid cat in the shed but don't want to remove them both as I don't want it insanely loud.

So this leads me to my question, obviously I am going to need a First de-cat pipe but to remove the other one I'm thinking about a twin box to keep the sound down a bit. I know Wifbitz do one but does anyone else make one? just to weigh up all my options.

Anyone have any video clips of the above setup? or any recommendations on what you would advice?

Jake

I'd leave the first cat in and just change the mid pipe. Removing both and using a twin box is likely to provide roughly the same amount of restriction. Also, I think NA's tend to be louder at idle with a fully decatted system

I'd leave the first cat in and just change the mid pipe. Removing both and using a twin box is likely to provide roughly the same amount of restriction. Also, I think NA's tend to be louder at idle with a fully decatted system

I would be happier with this, however im not sure if the ECU is designed to run on a full de-catted system and I have paid and ordered it now.

I have a TT car so it may not be completely relevant,

But i have an apexi twin box system on my supra and its relatively quiet on idle with a bit of noise high up the RPM, but not over the top,

personally i'll be looking for a new system some point this year, as i'm wanting something a bit louder

Yeah the thing is na's are considerably louder when de catted. If you think the cat and silencer make equal amount of resistance then maybe I should just fit my second decat and call that it.

Whifbitz 3" Twin Box? Not sure ir they do it for N/A's though.

I have a the HKS Hi-power Silent with 1 cat removed on mine Jake. Personally would not even think of taking the second cat out as well would be ridiculously loud.

I have a the HKS Hi-power Silent with 1 cat removed on mine Jake. Personally would not even think of taking the second cat out as well would be ridiculously loud.

I'm also currently runing the same set up at the moment and it sounds just right to me, not to quiet & not to loud. HKS Silent HI-power with stock manifold and first cat still in place but removed the second cat.

Thanks guys, there are indeed some very nice sounding systems out there, however I think my point has been lost. The New ECU is mapped for an exhaust as far as I'm aware, so trying to see if I do scrap all cats the best way of taming the sound. However if a cat ,silencer or bung have the same amount of resistance in air flow then I shall just ditch one cat and try that.

I would think a cat would be more restrictive than a silencer. Especially a 20 year old cat. I would fully decat it, then get an exhaust company to weld you a box in to second decat. You should be able to get it done to the volume you like.

Double de-cat it and stick a RSR on there and order some ear defenders job done

Remove the oem cats. then get a high flow stainless cat installed wont be much resistance and still cover you for police checks. And cut some noise

Double de-cat it and stick a RSR on there and order some ear defenders job done

Id rather my ears don't bleed when driving lol. Got to do DB this year in it dont want it droning on for 1000 miles

Remove the oem cats. then get a high flow stainless cat installed wont be much resistance and still cover you for police checks. And cut some noise

I would think a cat would be more restrictive than a silencer. Especially a 20 year old cat. I would fully decat it, then get an exhaust company to weld you a box in to second decat. You should be able to get it done to the volume you like.

Yeah they could be a good solutions, i will have to try find a decent company and have a chat to them.