Can someone help/explain which I need? I was looking at the Jap Inovations site and there are the two different types. I have an MY96 uk turbo with Magnex centre and backbox already.

Cheers

 

Anyone?

 

Closed neck is basically the same as the std downpipe but obviously without the CAT. The closed neck design has the wastegate area of the turbo blocked off like the std DP.
The open neck DP is opened up where the wastegate is giving better flow properties over the closed neck.
The only real benefit i can see for the closed neck is better flow than std due to the loss of the CAT but having the wastegate blanked off is not the best design

Rob

 

Go for the open neck DP. You will have to modify your turbo heat sheild slightly to clear but it is easy to do.

 

I personally can't see why anyone would want to buy a closed neck DP (unless of course, they were changing the downpipe for something other than performance gain reasons).

Matt

 

There are three basic down pipe designs. Closed Neck or Semi Closed Neck eg. Revolution, Open Neck eg. Hayward and Scott, or Twin down pipe eg. Scoobymania. The intention of the twin downpipe is to segregate waste gate gas flow from turbo gas flow.
There is a lot of debate about which is best and I am not convinced that I know the answer. Perhaps a totally seperate waste gate will have advantages but will also have disadvantages. At present I run a Revolution exhaust system with a totally open H+S open neck collector downpipe. However, the performance gain when I first fitted the Revolution system, complete with semi open neck downpipe was quite remarkable but this was before I carried out further major modifications. The Revolution system complete was certainly very cost effective and beneficial at that stage of development.

 

Cheers for help

Clive