As far as I remember, the thermostat that I got from IAP has the same disc on the bottom. I just went out and take a look at my GTV, there is nothing in the bypass hose.
Centerline listed two different hoses for the bypass hose, one for US car (cheaper) and one for Euro spec (more expensive)
Originally posted by papajam
The stat in the pic is made by Gates. P/N 33208 (I think).