Thanks for the replies guys, and to clarify a few points. Yes it is an 88 and it is running the turbo (Disco 200Tdi) and yes there is a down pipe attached exiting just below the chassis (I'll try and get a few pics up tomorrow). So is the important thing here is the bore of the exhaust pipe, as long as I use a 2.5" pipe I take it that the route or number of silencers aren't really that important?? I was worried that I needed 200Tdi specific silencers to create certain back pressures for the turbo or is it just about the flow of gas out of the exhaust??
Needing back pressure is a bit of a myth. It really stems from older petrol cars, where if you reduce back pressure they'd run like crap, because when you do this, you should really also adjust the fuelling and maybe even different jets in the carbs.
EFI engines can cope better and might just run a little rich, although a tune is still useful.
But you really want minimal back pressure on any exhaust system. With diesel it's even clearer cut, as diesels have no throttle plate and the turbo creates an massive resistance in it's own right.
So for a Tdi the only concern on an exhaust is flow rate. Too small a bore will strangle it and reduce power and make it not want to rev as well.
2.5" should be sufficient. But going bigger would cause no harm at all. The bigger the exhaust the greater the flow rate. The lower the EGT's. But big exhausts are difficult to route and if you aren't going for maximum power on a heavily tuned and modified engine, I really wouldn't worry.
I did have a chat with Steve Parker and he can sell me a specific system for my set up right from the turbo manifold all the way to the tail pipe which will use the existing hangers etc (if they are indeed still on mine, I'll have to check) for £320. I'll just have to get it delivered and then get it fitted, which I should be able to do myself. I want to weigh this up against getting my exhaust guy to fabricate something using the down pipe that is already there but I want to make sure I have him use the correct parts.I guess it's all down to cost at the end of the day.
As you have a down pipe fitted already, it seems someone has either fabbed one up, or you have one from someone like Steve Parkers already. Or if it's a standard Disco downpipe, then your engine has been mounted in a different way.
Maybe see if you can post some pics up.
But as you have a downpipe already, I suspect it might be cheaper to fab something up to it. But maybe more grunt work.
A Steve Parkers exhaust should just bolt straight on however. But if your engine has been mounted differently it may not work. The Steve Parkers one is designed to work if you've used the standard Series engine mounts in the stock locations.
I have the Steve Parkers exhaust on my 200Tdi 88. I admit I had the front wing off when installing it, so fitting the down pipe was relatively easy. It'd be a pain to do with the wing on, but probably doable.
The exhaust fitted fairly easily. And essentially just bolted together. It comes with new hangars which attach to the chassis in the stock locations (you'll still have these, as they are parts of the chassis).
Afraid I don't have any pics of the downpipe or installing it, but here it is fitted.
It does look like it stands out, I think this is because it is silver against the black chassis and I've not got any sill panels on. It does look like it's hanging a little low, but it is essentially following the route of the standard exhaust. And I suspect with a bit of jiggery pokery and loosening off of the clamps, it could be made to tuck up further. But it's actually fine off road and hasn't yet caused any issues.