83 gti

Hello can anybody give me advice/help?I've recently bought another gti this has the 8v mk2 engine fitted which I'm intending to fit the 3" jetex exhaust system to soon as well as a performance manifold.My question is this to I have to buy the mk2 manifold or is there a specific one for this engine change as per the 16v engine transplant.cheers

3"???

Why so big? You wont benefit from going over 2" power wise and it'll be a struggle to fit

I've never heard of any bigger than 2.5" on a mk1 and that was for a 1.8t

Waste of time on a DX engine

While I have no mk2 experience, I would expect the exhaust flange fitting to be the same as a 8 v mk1,  so you would me looking for a mk 1 gti  8 v  4 into 1 or 4-2-1 manifold i would think.

The MK2 had a different down pipe design, as the steering rack was moved and the down pipe was re-routed to a location that was above the power steering rack.

While the manifold will fit that is the 4-2 the down pipe will not.

On the mk1 frame the down pipes went through either a solid connection to the down pipe then a flexure fitting to the exhaust system.. that was under the steering rack.

The different types and there are 4 that I know of specific to the year and model of the mk1 over the years.

ie:  Golf and Cabriolets of pre-90 in the US had either the toilet bowl flange and spring clips, or the 4-2 and dual down hard mounted to a flexure that the Scirocco had, and there was the single point flexure fixed.

The mk1 cabriolet while the 90's version was a Digifant
and more engine wise shared the later MK2 it still had to have the Exhaust of the MK1.

I personally on my 90's Cabriolets have had either the OEM single hard mount with flexure at the top, where the weak part was the manifold.

I have converted my exhausts on the Cabbies I have owned to the Pacesetter header, the Raceland Cat delete header, and the g60 4-2 manifold and the tt tuning dual down to Cat.

Each had their own issues that I had to make design changes to get the fitment correct.  

ie: Pacesetter header had to have the pipes heated and bent to accommodate clearance issues of the pipe to the Steering rack.

The Raceland Cat Delete had to have an flexure added for engine torque.

The 4-2 g60 and tt-tuning dual down had to be welded to the pipe, while the flexures were at the manifold to down pipe for torque I had to come up with a way for each of them to add a heat shield to to prevent Baking of either my Power steering rack, and or CV boots on the differential.

Increasing from a 2 1/4 to 3" system while allows for easier flow, most of the components from the Down pipe back will either have to be modified at the front for the 3" or completely re-designed from the connection back, as using stock components will mean that you will have a bunch of reducers from 3" to 2 1/4….negating the expansion.

From first hand experience, increasing the diameter of the pipe and things from Stock to oversize will not gain you as much in performance as you expect.

Turbo's have a single down pipe connection.  But then again I have seen Dual turbos with dual downs…

Going from a Single down to Dual down will give you the breathing ability that you are probably expecting, and I noticed the difference in the Seat of the Pants feel of the cars.  

Also going from the stock pipe to the larger will lead to possible rubbing on  places and require some thought.

As in the clearance between the tank and the axle bends.  Will you gain that much, probably not.  A good aftermarket free-flow "Cat-Back" system will give you all the added breathability that going to "3" would give you with a lot less hassle….IMHO.