Hi, I currently have a piper cat back and want to get a decat but all the eBay ones seem to fit standard system. Has anyone brought a cheaper decat that fit straight to the piper system?

Thank you

Tris

Hi, I currently have a piper cat back and want to get a decat but all the eBay ones seem to fit standard system. Has anyone brought a cheaper decat that fit straight to the piper system?

Thank you

Tris

Hi Bud I answered your PM. (But reposted it anyay to potentially help others)

Unfortunately it was not a straight fit.

All the 1 piece and 2 piece decats are only a straight fit to the std exhaust as that std exhaust is thinner and longer past the center hook up points.

Unless you go for a expensive decat that is already longer to accommodate this you will be out of luck.

However it is not too bad to fix.

On a previous 1 piece decat i purchased a 6" reducer pipe and just clamped them together and fitted straight into my piper exhaust.

More recently i have a 2 piece toyo decat that i cut off the thinest section and had welded a wider and longer section which fits direct to the leftover pipe and then just fitted direct to the piper exhaust with a clamp. This is the cleanest way.

The only issue with the 3" 2 piece decats are the wide part that connects to the turbo manifold is smaller in inner diameter to the manifold so i kind of wonder how efficient the gases are coming out sometimes. For example my old 2.5" blameflame sports cat and downpipe and my original 1 piece 2.5" decat had a bigger / better inner diameter that matched the turbo manifold diameter. Hope that makes sense.

Here is the original 1 piece Decat that I added a reducer to the end to allow direct fitting to the piper system.

Here is the welded and longer section of the 2 piece decat that now fits straght into piper system.

This is the 2 piece exhaust to manifold end where i mentiond is thiner diameter.

Verses the 1 piece decat (can see less metal near bolt holes)

Add pic of the turbo manifold end. To me these diameters should be equal to get best flow.

Why did you change the 1 piece downpipe? Looks like it was perfect for the job? Where could I get one of these from?

Why did you change the 1 piece downpipe? Looks like it was perfect for the job? Where could I get one of these from?

Ebay.

Why did you change the 1 piece downpipe? Looks like it was perfect for the job? Where could I get one of these from?

I changed the 1 piece and sold it because I could not get friendly MOT tester and put back on the Sports cat. Then later decided to get another decat and went 2 piece as they are 3" diameter as apposed to a 1 piece being 2.5".

The 3" diameter is a little pointless though if the exist of exhaust gasses does not flow through a same size inner diameter top section.

Also the 1 piece was hitting the steering rack heat shield and was annoying but as i now have a S3 rack the heat shield is not in the same place, so could probably get away with a 1 piece now.

the more I hear about these niggling problems the more I think ill just get a custom made downpipe into a piper exhaust. its just easier in the long run I think..

Hi sorry for not replying to your PM - just got back from my hols.

My decat DP is 2.5"

My exhaust fitter welded it to the Piper system.

Thanks for the replies guys, Bowders did you find the two piece misses the steering rack heat shield? I stupidly brought the one piece and it hits and wont fit so gotta send it back....

Thanks

Tris

Thanks for the replies guys, Bowders did you find the two piece misses the steering rack heat shield? I stupidly brought the one piece and it hits and wont fit so gotta send it back....

Thanks

Tris

Hi Tris, Yes the 2 piece does miss the steering rack heat shield by quite a bit. The 1 piece is very close and you can get round that by bending the heat shield away or removing it. It did annoy me so that is why i got a 2 piece. Cheers. Mark