Hi all
As you might know, I am still in the planning phase of my A12 power upgrade. Now the next thing on my mind is the exhaust manifold. I have the TnPShow templates to make a exhaust flange. So I am thinking of getting a pipe bender and then making my own set of extractors. I might have the option of a mandrel pipe bender. Just need to talk to the guy if he is willing to bend pipes for me and at what price.
Now the burning question, please feel free to add your opinion on it.
Currently I am running a genuine GX 4-2-1 exhaust setup going into a 50mm pipe.
For a mild performance build A12 what do you think would be best for 7-8000rpm usage.
4-2-1 GX setup or a 4-1 setup.
I am tempted to 4-1 but with the low torque of a A12 engine, the 4-2-1 can just be a advantage.

Faark, i need to get the bakkie on a dyno, I have good bottom end torque and top end performance. Pulls clean to 7k rpm without a hint of performance drop.

The 4-1 TNT branch works for me, personally i think my motor is better balanced with the 4-1 than it would be with the 4-2-1, but then for a Gymkhana setup you need good bottom end torque and need to pull 1st to the end of the rpm range, you also need to exit a corner in 2nd at around 3k rpm and be able to get the revs up nice and quickly.

On a wet road the bakkie is already a biatch to drive, I do not want to know how it would be with a 4-2-1. To hard and I mean the first 10mm of throttle easily result to standing still.

On a road car, if you are going to drive it as you should, the 4-2-1 would probably be better ( if the road is dry ). If you plan to use it on the road and drive the crap out of it, high rpm, the 4-1 will be a good bet.

Yes you can build your own, I even think some engineering shops sell the 4-1 collector plates.

But @ R915 for a TNT/Cowley/Viper is it worth it.

Reason why I would do something like this is to get all the pipes at a equal length.

I have already gotten a quote. The flange I can get laser cut for +- R80.
The piping I think 6m length would be long enough and would cost, let's say, R100.
Then it is just bending and welding. Lets add another R200.
Total R380.
Much cheaper than a branch that is designed for a A14 engine that is sitting more to the back or front than a A12. I just can't remember. I don't want to buy a branch and then due to it designed for a A14 engine's position finding it fowling and difficult to fit.

A question. Those of you who bought extractors for A14 and fitted it to A12 engines that sits in a different position, did you have major problems? What problems did you experience with fitment.

any A series extractor should fit fairy much the same up and down or back and forth buy no more than 1/2"

the only problem is a12 going on a14/15 ... the engine mounts on an a14/15 sit about 30-40mm further back and some extractors hit but a14 exctractors on a12 would be fine

im making my own extractors for my 1200 ute atm. im making it all out of stainless 304 grade, i brought a bunch of mandrel 90 degree bends and about 4mtrs of pipe. if you google 'burns racing' that will give you a good idea on how to make your 4-1 merger collector, when your doing your extractor pipes i got told to make sure there within 2 inches in length n thats acceptable

i have exhaust flange plates semi finished to make your own extractor.

Thanks for the replies guys. Much appreciated.
Making the collector seems to be the most difficult part of the job.
Wait a minute.....
Maybe I can get a collector at a local exhaust shop. Some exhaust shops make extractors themselves. You just need to leave the car there for a day.
Maybe I must contact one of them to find out how much a already made collector costs.

Now the next question. What size pipe must I use on a hotted up A12GX engine for the extractor?

measure exhaust port size match the flange & suit pipe size or slightly larger pipe