Monaro VXR – Cats or no Cats?

[charlesr]

Hello all,

I just picked up my VXR on Friday, and I immediately noticed how ridiculously quiet it is for an engine of that size. I’m used to driving a very loud V8, so this is something I want to change asap.

I’m having a new rear sports box fitted to the VXR tomorrow, as I really want to hear that massive V8 properly. Currently I have the standard system fitted. I was just going to replace the back boxes, but in order to get the best tone (depth etc), would it be better to replace the system from the cats back?

Also, if I were to remove the cats too, would that be too loud? (I have a track day coming up with a 105db limit)

Thanks in advance guys,

Ch

[uk hsv]

If you are nr.Loughbrough call in to "Archie Moss" Vauxhall and have a listen to their 6.0l with full catback

[charlesr]

Hia,

I'd love to, but I'm in East Sussex. From what you say, I take it that a cat back straight through system will be sufficient?

Mine's a 5.7 by the way.

Thanks mate

Ch

[uk hsv]

In which case get over to "Green's" of Rainham (Kent)and check out the "main mans" Classic VXR...........



>> Edited by uk hsv on Sunday 15th May 22:10

[charlesr]

I don't think I'll have time to get there before I get the system changed - It's booked in at 4pm and I'm at work until 3.

So, do you think I should leave the cats where they are for the time being?

ch

[dan_the_man]

Cats are for pussies - get rid of them, even without them it's too quiet but you can release a bit more power if you junk them.

[caspy]

Leave the cats. Unless u change headers prob wont make any diff, and will not affect performance until u in a very high state of tune.

[charlesr]

Thanks for the advice guys - what about the noise levels? Would it still be below 105db in either setup do you think?

Ch

[caspy]

As i learned at the weekend, 105db is very very loud, the only Forum car i have heard that gets in trouble is V8HSV, but he has a 9inch drainpipe and nothing else on his (maybe a bit of bling at the end).

Which track day ?

[charlesr]

Thanks - will probably do the whole system then.

Brands Hatch this Sunday!

[A57 HSV]

I'd agree with Caspy, get bigger headers. The reduced back pressure from removing the cats can cause problems that have been discussed here in the past. These can be overcome by the right ECU tuning, but that's another issue.
A big cat back system should satisfy your need for V8 sound, just be aware that cruising at m/way speeds will probably be at bit "drony".
I'd try the cat back option first & see how you get on, then do the headers later.

>> Edited by A57 HSV on Monday 16th May 10:41

[charlesr]

Excellent. Thanks mate - that sounds like good advice.
Ch

[V8HSV]

For the record I have 2 1/2" straight through system with one rear box (about half the size of the original) that has me banned from every track on noise grounds. If you stand by the car it is not that bad but if you are a mile away it is reminisent of a cross between a Ducatti and a 2nd WW plane!

On the road it is quiet until throttle is applied, passengers (two 20 yr old girls) on a recent trip to Holland remarked how quiet it is at speed crusing until it is 'given some' then they remarked 'it just growls in anger!'

Yes you have to pitch the right gear against speed to stop it droning but what the hell, pure NASCAR sounds on tap, keeps me speeding excessively too (11 PP).

[charlesr]

Take it to Spa -I took my Cerbera (4.5 with a straight through system too) over there in April. Fantastic track with no noise limits.

I'd best keep the cats in then for this weekend!

Ch

[stu harris]

Don't forget chaps the 5.7 VXR runs with tubular headers , to get decent sound you don't need to touch these.....just the rest of the system

Stu

[charlesr]

Just the cats back, yes? (I know I'm labouring the point now!)

[caspy]

Cat back on 5.7 VXR is ideal. One thing at a time.

[charlesr]

Hurray! Thats sorted then. It'll be interesting to see how she sounds after the swap over. Will tell you tommorow.

Thank you all for all your help.

Ch

[SS UTE]

I junked my cats and got an extra 12hp with a little bit of playing from Wortec. It's louder but not over the top. Now thinking of getting rid of the remaining box and running straight thru.

[V8HSV]

SS UTE GO FOR IT!

Did you get a bigger uplift in torque?