Had new downpipe fitted today, thought i'd go to 2.75" as my turbo elbow is that diametre!
So i thought they would fit downpipe and then TAPER the downpipe in some way down to the 2.5" de cat....

They've have simply butted the 2 up i think???
Is this normal?? I know it would be better to have same size pipe right through, but funds would not allow at the mo, so i thought the flow would not be affected that much if there were a taper... but theres not!
will this have a negative effect on performance???

Nick

It's hard to taper a stainless steel pipe without cuts and welds that could eventually fail.
Joining the two is how most exhaust people would do it, I think the Blueflame steps down at the flexy joint at the end of the downpipe.

To be honest, the exhaust gas has lost quite a bit of heat and so velocity by the time it's at the end of the downpipe so the reduction in size at that point isn't quite as big an issue.

Thats what i was hoping to hear!! thanks!!!

Nick