I am considering having the cat removed from my 1988 Pontiac Bonneville'* exhaust system and having a piece of straight-through pipe welded in instead. Reason being I want more power... cheaply. It has a GM 3800 Series I V6, is currently set up as stock, and is rated at 165bhp and 210 lb-ft of torque so it'* not exactly making the best use of its 3.8 litres.

My question is will there be any unwanted side effects from removing the cat? I'm particualrlry concerned that removing the cat might affect the reading from the oxygen sensor, possibly leading to the engine running at the wrong fuel mixture. Would this be the case? Would it also have a negative effect on fuel consumption?

Any other suggests for cheap horsepower gains?

Cheers guys!

You'll lose low-end torque. I had one off my 95 supercharged for a week (until my new one arrived). You can't out-flow it. I personally think it will harm performance.

only reason to remove it for performance is if it is plugged

The O2 is before the cat, so removing it won't affect the reading.

Of course. Silly me!