I notice there are a few mild steel exhausts with stainless mufflers for sale. Is there a big tone difference or am I not seeing some sort of benefit from stainless?

osonvs, cats are optional pre09 in NZ, I had mine cut off and replaced with a straight pipe-you can hear the turbo spool now --AWESOME! You will need a tune after this,but if your doing work anyway- why not. It gets rid of the main restriction in the exhaust system.

Ummm.. Are all those calculations made from the outside diameter of the pipe?

If so then they need to be redone taking into account the wall thickness (usually #16 1.6mm)

I was enquiring on another forum, looking for the best possible exhust system for my 500+ hp cloevo that going in to my XF GHia.. A member posted a link to a site in the "States" that does oval exhausts.. It looks the gods and would most definately flow well and fix an ground clearance issues..

OVAL EXHAUST PIPE LINK

Does anyone know if anyone in Oz supply this ??

I can do oval piping, bends, transitions etc.

PM me...

Read some flow testing one day showing a same sized straight through muffler flowed about 15% less than same sized straight pipe...not sure if its accurate but on my last turbo car I had 2.5 inch exhaust (very small motor) with 3 inch mufflers (magnaflow) 3 inch high flowing cat and worked real good.

Edited September 3, 201115 yr by Garrettba03

Hey Guys I Have a BA XR6 Turbo. . Only mods are strengthened diff and strengthened auto. Also an air box and custom tune running 9psi. I recently put a new exhaust on its 3.5 cat back and 4 inch dump pipe. Question is will this be a good exhaust for the set up I have and should I get a re tune quite new to cars so just wanting expert opinion on the matter

Cheers

Did you change the cat?

Probably still worth getting a retune just to be safe.

Did you change the cat?

Probably still worth getting a retune just to be safe.

Yes mate changed cat whole exhaust is new. Even without re-tune so much better on boost. But runs a little bit rougher I rand autotechnique in Ferntreegully. They recommend a re-tune minor changes and maybe a new boost controller due to the 4 inch pipe been know to spike now and again.

Not that I am endorsing APS products but I thought this was a decent write up and has pipe calcs inc'd;

http://www.airpowersystems.com/falcon/exhaust/exhaust.htm

3.5" minimum. Or a mix of 3.5" and twin 2.5"

People don't take into account wall thickness so all those measurements are flawed