AAGGGHHHHH!!! eek! What are you guys thinking of?? DO NOT DISCONNECT THE LAMBDA. The management system will pick up the fault codes and will revert to maximum enrichment setting. Fuel consumption will be very poor- no better than 30mpg (when it should be 40 or higher) and there will be NO performance increase.
The mixture will be richer than the 12 to 1 at which maximum power is produced. The catalytic converter may also overheat due to overfuelling which may wreck it. eek!
I would advise you not to buy a cheap sensor. You get what you pay for. Both in terms of fuel economy and performance.
Another minus point is that the wiring may not be very good. It may require an extra wiring part or the wires will be four times as long as they should be.
Advice: Go to a motor factor eg Partco and get an OE quality sensor. NTK sensors will probably cost about £50 + vat- I've already fitted them to 145/146s and they work and last.
Its really not worth getting a crap part and risking driveability problems. It may also make diagnosing future management problems much harder.
One final point is that as I am a hands on partner in a garage business, I find that a standard well maintained car will almost always out-perform a not so well maintained modified car!
The moral of the story is if you fit a cheap lambda sensor and have a chipped, cammed and flowed engine with manifolds and filter, the fortysomething school teacher in a hurry home will still burn you off at the lights if it aint all done right. Believe me, I see more wrongs than rights on young lads cars. Before you wonder, I'm not some old git. I'm a proper petrolhead whose past/present cars have had the aforementioned mods.... and they were/are 'kin quick.