I installed the Mock extractors and cat today also. Although im no expert, the setup certainly seems professional, all of the welds are good quality, and internally seems very smooth with no obvious internal restrictions of any kind. Only thing that there was no bolt holes in the last flange for the centre transmission mount, so ill have to go down to the exhaust place and get them to weld something up.
Everything bolted up fine, other than 1 bolt hole being slightly offset in the main flange to the head, requiring me to grind the hole a little bigger....Strange thing was the old bolts went into this hole fine....
Car sounds more 'burbly' and certainly pulls harder up top (I realised after pulling off the old exhaust that the cat was on it last legs) I think fuel economy has noticably improved but its a bit early to tell at this stage....
1993 ED XR6 M5 (1 of 329)
Turbo on the way!!
1993 EBII Fairmont (Now wrecking, PM if you want any parts)
1988 Nissan R31 Skyline