Looking to do an exhaust system for my V8 and need some advice on what I am after, performance and little or no noise. (still want to keep the luxurious flow to the car)
It will be a cat back system with new high flow cats. What I was thinking was,
from cats -> 2 separate non joining pipes -> X-connection down the middle -> 2 hot dog resonators -> Oval mufflers and dual tipped mufflers =)
Now, i know sizes of pipes has to do something with sound, so is 2.25" piping or 2" piping better?
Any other suggestions/ideas are needed before i pull the wallet out
Monday, August 01, 2005 - 04:21 pm, by: David Vaughan
Duy, like Don said, if you use Search on the ALSC archive I er, droned quite a bit about the research and changes I made having exactly the same aims as you. It is worth reading those questions and the contributions of other people there but a quick summary here is: - I did not bother changing the cats. Peter Scott has demonstrated that they make negligible difference to air flow so I looked on it as money for nothing. It is the four rear mufflers that matter. - Can not comment on X vs H because I kept the existing collector. - I was going to get hot dogs but was persuaded out of it by the seller who was pretty committed to selling me the changes I needed rather than just short term lining of his own pocket ( Ian lampl, Powatone Canberra). Hot dogs would make it quieter but skipping them makes it faster, and the tone is very good - at cruise up to 120 (under the radar) it is absolutely no louder than stock (measured with a sound meter in the cabin). - My system is 2.25" offset straight through oval Redbacks. Gain=12 rwkw or over 8% and my wife, who is noise-averse and outspoken, has never once commented.
David Vaughan TryHard Soarer GT Limited (4.0L V8) and is300 (3.0L il6)
Monday, August 01, 2005 - 04:27 pm, by: David Vaughan
Afterthought: If you do want to replace the cats, have you considered Rush Headers at the same time? You see, fitting them requires that you change the cats so, back to front, if you are replacing the cats anyway then there is another big improvement you can make to the flow. If you fit the V8 headers, then you might want to fit the hot dogs to tone it down a bit. You will still get a further gain in power.
If you have not heard of Rush Headers, go to www.rushimports.com.au, home of Neil who appears to have made a sex change from Grandpa to Aunty in the recent forum switch.
Sorry David, first thing I would have done on ALSC was do a search, but didn't know the old archives were here (only now as i checked my email and actually didn't click the 1 day postings
Headers and extractors was the first option I was going to go. But, actually after driving the car for a while, just liked the smooth sound it made.
Ok cats wont be changed, ill do your system. WOW 12rwkw gain, not bad!!! I'll salvage through the archives. (5 minutes later), I just checked the old archives and I cant find the post of it. Is there any possibility of throwing me that link?
Ohh don't worry about Neil, I make up names for that prick every time i ring him, which is everyday hee hee hee
David Vaughan TryHard Soarer GT Limited (4.0L V8) and is300 (3.0L il6)
I've got extractors down to cats, to resonators and H pipe, then to generic oval rear mufflers, all 2.25" pipe. Sounds very nice IMO, kinda loud outside the car. Inside it sounds pretty lumpy when you stand on the go pedal (read: not loud) with windows up. When just cruising around town or highway, sound is hardly noticable, if at all.
At the moment theres this gaping big hole where the exhaust mount was welded to that's decided it didn't like being there anymore. Damn it's loud, will be fixed soon!
Yours sounds nice Avin, but at this point I want to do cat back and little sound. When i want to do headers and all, then ill add the rest on and it will sound like yours hehe
Tuesday, August 09, 2005 - 08:46 pm, by: Kris Blackler
mine recently got complianced and they according to my mechanic put shitty cats on. i have been told it is under powered so decided to do the exhaust. im getting two new high flow cats and getting rid of the back 4 mufflers for two high flowing mufflers. will i notice much of an increase in power?
Put new headers on when you're at it (Neil's are good). It will save you redoing the exhaust later. It also gives another bump in rwkw. Mine was +19 rwkw with headers and exhaust.
Wednesday, August 10, 2005 - 12:12 pm, by: Damien Smith
Yeah, do what Benny said Duy because the system with headers is different to without headers - it's not really a before cat/after cat situation as the whole lot changes.
Kris, you'll get some increase but best to just go the whole hog as the standard exhaust manifold is rubbish.
David Vaughan TryHard Soarer GT-L (4.0 V8) and is300 (3.0 VVT-i 6)
Wednesday, August 10, 2005 - 12:46 pm, by: David Vaughan
Duy, on the 28th you can see and hear both my and Benny's systems (as well as a dozen others) and also understand the comparative costs and gains. I have no stake in what you do but my usual approach to this sort of problem is to choose patience and direct comparison for a good decision.
Kris, there were three components to your choice: performance, noise and wallet. Damien is quite right that the standard manifold is a piece of crap but then in performance terms so are the rear mufflers. Every step of performance will increase the noise. I think there is enough information in the above to help you choose but if you make the flying leap to the complete system then I assume that you will have costed in taking a step back again (more muffling) if it is too loud. If headers appeal, one approach might be to do them and the cats and then consider the rear mufflers after you know where you are up to on the dyno and the noise perception.