Exhaust speculation

[doommachine]

OK, so I am bored and thinking about exhausts.

With the RVR, I really want to maintain a sleeper attitude as much as possible. (yeah.. that front bumper and huge intercooler is subtle )

Anyway, exhaust wise - especially with taller vehicles - seeing a 3" stainless pipe under the car makes me think.. hmm.. is that stock? I don't think so... so, I want to avoid that.

What I'm thinking is effectively an xr6 turbo exhaust (I may even get all the bits and pieces like muffler, cats, etc from an actual XR6, depending on cost vs aftermarket stuff) - 3" dump and front pipe going into the cat (I would at least use the xr6 turbo cat as it is 3" in and dual 2.25" out), then from there a dual 2.25" system.

Surface area wise, I will have a bigger than 3" exhaust, albeit in 2 pipes (3" = about 7.3 sq cm, 2.25" = 3.9 so dual = about 8).

Plus it will not hang so low and be so obvious.

But there MUST be a catch - with the smaller pipes, what sort of difference will there be in terms of gas velocity? Faster, slower? I'm sure I've read posts about people replacing stock xr6 turbo exhausts with a single 3" and gaining power.. would that be down to mufflers etc or are we talking a difference due to the physical properties of the pipe?

 

[bazeng]

Going twin pipes isn't much of an issue. I've seen plenty of XR6 turbo's running 350+kw's with twin pipes instead of one. The only downside would be the cost to fabricate (multiply by 2) and also the additional weight.

You just have to ensure good merge pipes and dividers.

If you are going to the trouble of twin pipes, it would be better to go oval pipes and use up all of the additional external area of going twin pipes but once again, oval pipes are expensive because the fabricator will need to cut whatever pipe in half, then join them with some flat.

I say go for it mate.

As for cats, you can get great metal cats for a decent price (about 300 dollars). Go for the largest cat possible. 4" cats are now available with a 5" body.

The XR6 turbo I've talking about has run high 10's with single pipes up front and twins at the rear going to a single muffler.

 

[doommachine]

Ah I wanted to go with smaller cats etc... less obvious.

Also going twin smaller pipes costwise should be reasonably similar in price to a single 3" system? - an exhaust fabricator in my home town once quoted me a twin 2" system for lower than a single 2.5".

 

[JayRome]

Ah I wanted to go with smaller cats etc... less obvious.

Also going twin smaller pipes costwise should be reasonably similar in price to a single 3" system? - an exhaust fabricator in my home town once quoted me a twin 2" system for lower than a single 2.5".

i would just go 3" all the way, just get more bends to make it hug the body..... other wise i have done twin 2.25" systems, but for the price of labour, cause your basicly making X2 identical system... it may not be worth it...

 

[milkandoj]

Basically you dont want to draw attention yeah but a good flowing exhaust?

If you want to not to stick out mild steel rather than stainless would hide it a bit. AS still go 2.5 or 3 inch single.

Muffler: rather than use a cannon get an oval muffler, one that is dull stainless and not shiny.

Lukey, magnaflow and x-force make strait through oval mufflers so it will be deep, shut the car more than a narrow cannon up but flow well.
Lukey reckon their ultraflow range which is strait through take out 10-15dB. The turbo flow range is mean to flow almost as well but take something like 18dB + out. Not strait through.


Paint it black: the muffler with white knight hi temp, its rated to 540 C. Or do the cat back section aswell.

Is will make it look stockish or even at least not like a fully sick shiny stainless exhaust with a cannon. If the police see it its looks more like you dont want to draw attention to yourself, hence your not a wanker.

 

[Entaran]

My thoughts would be... avoid stainless. Use mild, after 3 months or less on the car it'll look like any other exhaust. Also if you really want the "factory" look, steal some heatshields off the bottom of cats from commodores or whatever and attach them to whatever cat you buy. Make sure the exhaust is regularly flanged (factory systems are almost always flanged every 2 meters or less). Oh and it has to be relatively quiet.

 

[doommachine]

Oh I don't care about noise etc that much.. it can be reasonably noisy, it's more I don't want to have an obvious exhaust on the car, not for the cops, but for WRX drivers if it's loud people dont think twice, but they see cannon and they think RAAAAAAACE you know?

Also I wanna try something different, never seen a 4g.. well a turbo 4 banger really, running a true twin system.

The other thing I was thinking was having a 3" out of the turbine and a 2" pipe out of the wastegate... sort of a muffled screamer pipe. would look pretty sweet at the back haha...