Xsi horrendously down on power.

[Ed Doe]

Mines blowing ont he centre box but it still feels just as fast as always.

**Awaits ohhhh its a 1.8 though... even walking is quicker!**

Depends where it is on the centre-box, but in general reducing back-pressure will marginally reduce low-end and mid-range torque, but will marginally raise top-end power, as the engine can expel gasses more easily.

Depending on the size of the hole, it will affect it to varying extents, and it's doubtful you'll 'feel' the loss, as it will feel 'quicker' at the top-end. However, the area under your 'power graph' may be marginally smaller, meaning overall acceleration may actually be less.

The effect will be minimal really, even if you're running with a hooting split pre-cat and it sounds like the earth is literally ending, but the difference of a few hp there, coupled with a few lost through needing a service can easily reduce the power to weight ratio, and as I said, gear ratios play a big part in acceleration. That's why gti6's with 'only' 167hp are still not too far off, and in some cases quicker than much newer more powerful stuff like golf gtis and type r's. But it's also why they literally suck balls at economy; the box is so short!!!



Yes Matt, your straight-through back-box will be reducing back-pressure and will reduce your torque as above. I'm sure its the same thing with the eXceSs-pie, but the standard '6 exhaust was certainly very well designed out of the box, and it works with the induction-side to aid mid-range torque whilst also flowing well for the power. There were a whole load of threads about this a while back on the '6 forum. Unless your cammed and bodied to buggery, or boosted, you don't really need to run a less-restrictive back-box...

EDIT:
Had a quick look for a couple of the threads about it:
http://www.306gti6.com/forum/showthread.php?id=141587
http://www.306gti6.com/forum/showthread.php?id=146944