Is anyone out there running a Catless NA? Does it make a difference and how much louder is it? I have a pair of frontpipes ready to go on but im umming and arring whether to add a small pair of silencers to them because being an old fart, im past the stage of loud exhausts. The car has a Mongoose system on it now and its just the right side of bearable noise on a long Journey .

I run a decatted TT, so I can't say for definite, but I have heard that an NA is VERY LOUD without the cats. With the TT, the turbos themselves do dampen the noise slightly by disturbing the airflow in the exhaust system, but on NA it'd just be engine/backbox/NOISE!! :eek:

The reduced back pressure will also hurt performance and can introduce some very unpleasant resonance at motorway speeds - deCAT pipes with small expansion silencers in place of the CATs should do the trick.

Hi mate,

 

I have de-cat pipes on my TT that have small resonators in them already, and having got used to my last Zed having no resonators I'm thinking of having them removed.

 

Let me know if you fancy a swap! :cool:

Thanks guys.

I have heard various stories about performance issues regarding Back pressure. Some say it hurts performance. some say it unleashes more power. Others say its just loud.

The pipes I have are a pair of Standard frontpipes with cats attached but my plans are to bypass them either straight through or with a small pair of Cherry Bomb type silencers in there place.

I had my NA decatted after good advice from this forum. It increased performance (subjectively) with the chip and induction. I had 190 at the wheels with those mods so for an NA I think this was very reasonable. From what others have said I would say if the decatting reduced back pressure, it was a good thing. I had the exhaust and decat done first and I did notice a bit more power lower down I think - still it was only my imression and could have been imagination.

 

I initially liked the noise from the car with standard exhaust- I felt I heard the engine revving, not the exhaust blowing, but after I had got used to the noise, I loved it. The exhaust fitter said 60% of the noise would come through the decatting being done, but it was never too loud to listen to the stereo. Most of the time I just listened to the car though...

I considered adding silencers in the middle but I think it is a waste of time- unnecessary faffing about in the end. I just enjoyed the sound when I got used to it

Mine has no cats with HKS super drager Ex. It IS quite loud but also a very nice tone.

supposed to give extra BHP, say up to 10 at max rev.???

ive got a straight through system on my NA!

had medium silencers put in and although took a bit of the edge off the sound it didnt make too much difference to it, is still quite loud

but like rich said, you do get used to it

Cheers Guys. I will try it both ways.......... Is there an innuendo in there?