Dump pipe.

[JimX]

Took the car into Midas last week to change the gearbox oil, and also had them check out the exhaust because to me it didn't seem to match what the previous owner had told me. I had been told by the previous owner that it was 3" cat-back only (he didn't do it himself, it was like this from Japan) but I was pretty sure the front pipe was as wide as the bit behind the cat, so I had the guys at Midas measure it for me.

Imagine my pleasant surprise when I discovered that it was actually a full 3.5" system except for the dump pipe, which is smaller and I presume stock. So I've saved a few hundred bucks on the front pipe and high-flow cat because it already has them! Obviously the previous owner had only seen the narrow dump pipe, and the wider bit near the muffler, and assumed it was cat-back only.

My question is replacing that really short dump pipe with a wider one going to make that much of a difference? Midas say they can make me a custom 3.5" Mandrel one to match the rest of the system for around $160, does this sound like a good deal?

[rev210]

Originally posted by JimX

My question is replacing that really short dump pipe with a wider one going to make that much of a difference? Midas say they can make me a custom 3.5" Mandrel one to match the rest of the system for around $160, does this sound like a good deal?

The stock 'dump pipe' (straight off the turbo) is made of cast iron and is certainly worth throwing away. Mine was really badly matched to the turbo outlet, so when I bolted the dump pipe on it was quite noticably better.

[Guest INASNT]

i will have my 3 inch dump with seperate pipe for wastegate comin in this week from sydney!

$160 is a bit cheap i dont think they realise they have to get the flange off the turbo laser cut to match the housing for the new dump

[BOOSTMEISTER]

On a 33, a well designed dump pipe in 3.5" can yeld 30hp so its worth every cent. INASNT is spot on with the price. The laser cut will probably add another $50 or so if you are lucky.

[CMS Drifter]

Can u post any pix when you get your dump pipe?

Coz I'm lookin at gettin one when the wallet will allow, but JMS want $350 for theirs.

Where did u get yours from?

Does it have the separate watsegate pipe plumbed back in further down?

Cheers

[Guest INASNT]

Originally posted by CMS Drifter

Can u post any pix when you get your dump pipe?

Coz I'm lookin at gettin one when the wallet will allow, but JMS want $350 for theirs.

Where did u get yours from?

Does it have the separate watsegate pipe plumbed back in further down?

Cheers

i am getting mine from arrow diffs in sydney, i was just about to tell them to get stuffed coz its been 3 weeks since i ordered the damn thing, and hes excuse was that the laser cutters was fully booked up and took 2 bloody weeks to get them done!

should be in by next monday!

It has seperate pipe for wastegate that rejoin right before the flange!!

[doxximus]

what is the standared exhaust and dump pipe size for a gtst?

[JimX]

INASNT, I'm not sure but I think the guy might have mentioned something about cutting the flange. I'll confirm that with him before I do anything though, don't want a huge 3.5" system running off a 2" flange

The pre-fab'd exhaust parts tend to cost more I've found, when I had the Commodore I got a price on a balance pipe and it was about $200 for a special "cross piece". I took it to the place which made my custom exhaust and they charged me about $60 inc. labour for virtually the same thing.

But anyway, I'll find out more before I do anything. Dump pipes are really simple. Provided you have the flange the right size and it's a mandrel bend with minimal or no internal burrs, you only have to worry about the grade of the steel used and what diameter it is.

[Guest INASNT]

Originally posted by JimX

INASNT, I'm not sure but I think the guy might have mentioned something about cutting the flange. I'll confirm that with him before I do anything though, don't want a huge 3.5" system running off a 2" flange

The pre-fab'd exhaust parts tend to cost more I've found, when I had the Commodore I got a price on a balance pipe and it was about $200 for a special "cross piece". I took it to the place which made my custom exhaust and they charged me about $60 inc. labour for virtually the same thing.  

But anyway, I'll find out more before I do anything. Dump pipes are really simple. Provided you have the flange the right size and it's a mandrel bend with minimal or no internal burrs, you only have to worry about the grade of the steel used and what diameter it is.

its 304 stainless steel!

there no point going for 316 or marine grade stainless stell as it would crack under the constant heat passing through it