Torque is a measurement of how much work an engine does, while power is a measure of how fast it can work. Since horsepower is calculated from torque, you need to aim for the biggest possible torque value over the broadest-possible rpm range.
If you want more torque the conventional method is to increase displacement. Bigger cylinders and a longer stroke will give the greatest cylinder volume and piston area. Thats why american muscle cars tend to have 5.7 V6 engines minimum.
Obviously on a 1.2 bravo you cant expect to make any real change to your cylinder volume or piston area. so the next best way to increase torque is to increase engine efficiency. There are millions (well ok dozens) of ways to do this, but it usually results in a loss somewhere on the power curve.
A good way to increase torque is reducing friction. you can get the cylinder chambers 'smoothed', you can get special coating on the pistons and piston rings, you can even get crankshaft bearings aligned or something like that. its hard to tell what kind of gains you will get taking this route, but i've read about excellent gains in magazines. friction reduction is an expensive option so i wouldnt recommend it.
A better way to increase torque (imo) is combustion efficency. basically getting the air/fuel mix right and having a well timed good spark. this is where remaps and chips come in. your ecu is set to maintain fuel efficency, ensure engine wear is reduced, run on poor quality fuels and reduce emissions. a good remap will focus on obtaining the best power and torque curves possible with the engine you have, screw the environment (and usually your engine internals over time).
Compression ratio is also a popular way to increase torque. Higher comression ratio will equal more torque. you can use a cam kit to increase compression ratio, but going too far down the compression ratio route often leads to detonation. you need to use as much compression as possible relative to the cam profile to increase low-end torque (without detonating). i like this route and i think any 'real' car would have at least a kent cam kit style upgrade (as well as everything else).
Obvioulsy valve timing can give you some good gains too, getting the camshaft timing right will make sure you get the most out of your displacement. if intake valves close early cylinder pressure builds sooner. increasing low-speed torque due to greater cylinder pressures. but it means that the engine is having to work harder to compress the charge. delaying the exhaust-valve opening will allow you to take advantage of all the energy you can from combustion. a quick-opening exhaust valve can be used, but again there are tradeoffs (there always is)
Cylinder head mods are also a good method, gettting the head gas flowed or 'ported' will give top end gains. bigger valves are also a great way to increase torque, the ford zetec engines had small valves, i've seen zetec engines with upgraded bigger valves and a shorter camshaft profile that had great gains. not hard to do, but again not a very cheap option (non of them are)
Exhaust system back pressure is very bad for torque, getting a decent quality full system desinged for the car will give gains. a 4into1 manifold is ther best bit to get, then a highflow cat (or decat pipe) a backbox is just for noise and looks but it can help a little bit.
Igntion timing should be set to match your other mods, a faster burning charge will require less timing, while a slower burning charge needs more timing. easy to get gains here buy it depends on what else you've done first.
Obvioulsy getting cold air into the engine will increase torque, so a k&n with a cold air feed pipe will give gains and its the easiest and cheapest option, but also one of the least effective, it is more successful when coupled with other mods.
the main thing to remeber about all of this is that your engine is easy to bugger up, all these ideas can in theory improve your torque and performance, but its easy to get things wrong and actualy spend a fortune making your car drive like a shed.
the best way to increase torque, absolutely the best, is to get a better car. its the cheapest, most reliable, easiest way and your car wil last more than a few months and will even pass MOT's. you could sell your car and get a 1.6 bravo instead (no difference in price), the only extra it will cost you is insurance and petrol. thats still a lot cheaper than the other options. a remap on your car would be more than the annual difference to getting a 1.6. the 1.6 has 110lb/ft torque, which is good for a standard 1.6. surely its the most sensible option. then you can do the easy reliable mods (air filter & exhaust) and just live with it. i know i'm boring and its a lot of fun getting the tools out, but until you win the lotto its just not worth it. face it a 1.6 is what you need.
