I've been collecting exhaust parts for my 2005 STI for a few weeks now so I can go full decat ready for my remap on the 5th.

My plan was to take the car to a Subaru specialist, have them service/MOT the car and then fit the decat, fuel pump and boost solenoid before having Andrew Carr remap it.

I want to make sure my exhaust bits are actually compatible though, as they don't match the parts on my car!

My car has got a PPP Sports Cat currently, with some kind of bodged second decat pipe with a flexi joint which is blowing, then the resonated centre, then PPP backbox.

I intend to keep the PPP backbox and replace the downpipe, second cat pipe and centre section.

The parts I've bought are as follows:













What I'm struggling to get my head around, is that my PPP downpipe is more "vertical" and because of that the bodge-pipe I've got between my current centre and PPP downpipe is longer than the second decat pipe I've got pictured above. I'm sure if/when I do a trial fit it will all make sense, but would just like some words of encouragement first.

Second is the rotation of the parts and hangar positions - will they all be right for my car? The second decat pipe for example has got the bolt holes in totally different places at each end, so I think the order I've got pictured is right, but the insert bit doesn't go into the downpipe very easily... maybe it needs whacking in a bit?

Does this all look right to everybody? Hopefully will do a trial fit at the weekend to answer all my questions - but if it's all obviously wrong, I need to know ASAP so I can order another system!

Cheers

 

It looks to me that you've got the centre pipe the wrong way round, other than that it looks as if it should fit

 

Ah Ok thanks mate.

I'm concerned about the "second cat pipe" or the "middle one" in terms of my pictures.

It's got a connector like follows:


As far as I'm aware, that's intended to house the "donut" gasket and spring bolts between this pipe and the long centre section. Problem is, the bolt holes at the OTHER end of the pipe don't line up with the bolt holes on the downpipe if I do it that way around...

Infact, the bolt holes barely line up at all between the downpipe and the second cat pipe. I think my downpipe is wrong

 

I've just had a scurry about under the car, and I've noted where all the hangers are. That's told me that my second cat pipe does indeed need flipping so it looks more like the following:



The hole for the lambda sensor has now flipped sides, my current setup has the lambda sensor on t'other side but that's an easy change... it's just a plug on a wire!

This now means that my bolt holes between downpipe and second cat pipe are WAY off.



This photo has the right hand bolt hole (out of shot) all lined up... look how far out the left one is!



So, either I "make it fit" with some kind of fabricated adaptor, or I try to find the correct downpipe.

I've got till the 1st June to sort it either way. Is there an off the shelf adaptor I'm missing or something, or is this just a mismatch of parts?

 

The downpipe looks like 3" reducing to 2.5" then you've got a 3" centre section

 

The bore of all three pipes is 2.5", just been out to double check!

I just called H&S. The distance between the bolt holes on the 2.5" downpipe on their website matches the 103mm distance which mine has got - so ordering a new pipe from H&S won't help.

My bolt gap is more like 115mm on the receiving end of the second pipe.

 

If there is room for the bolt heads on the flange on the second pipe you could mark the hole centres on the face of the flange then drill two new holes

 

or slot the holes with a file

 

im pretty certain your 2nd decat pipe is meant to mate to this type of downpipe.

Click me

there are earlier & later type downpipes in newage, you have the later and as far as i know there isnt an off the shelf 2nd decat for them

 

Thanks Gambit.

I was under the impression that the type of DP pictured in your post didn't even require a second pipe, it just bolted direct to the centre section.

I think I'll consider getting a H&S "all in one" pipe containing both the vertical downpipe and the horizontal second pipe all in one construction. I considered redrilling the flange to make it fit, but the whole reason I'm swapping my system is to replace some questionable "bodged" joins...

 

Been back and forth with emails and photographs to H&S and come to the conclusion that the DP is for a 2.5l 2006-07 car.

I've ordered the 2.0 equivalent so hopefully that'll sort it and I can absorb some of the loss on ebay.

Does that sound about right to everyone else? The Flange on the 2.5l downpipe being smaller than the 2.0 one?

 

yep its identical to my hawk

 

Sweet. Hopefully the 2.0 equivalent should be the answer to my mystery then, should receive delivery of it tomorrow

Thanks Gambit.