Well start with a reasonable exhaust system and air filter. Don't expect miracles but it will help make the engine more responsive in most cases.
A good head should add to torque everywhere in the rev range. I recommend Blydenstein engineering (tel number somewhere on MIG, do a search in the Mechanical and Electrical section). I reckon about 10BHP more for a B+ head from Blydenstein.
A higher lift and duration cam will push the torque up the rev range and since power is torquexrpm then you get more power. A fast road cam will add around 5BHP and not lose you too much. I had a fast road cam in my 1.3 and it was fine about 1500rpm so it was sane.
The most we can get of the C14SE 1.4 MPi engine is 117PS, but for most fast road useage we'd recommend an upgrade to 107PS spec, which adds an extra 20Nm of torque.
The package consists of:-
10.8:1 compression gas-flowed cylinder head and a twin outlet manifold with tubular downpipes. Beyond this we can offer a revised ECU map and a 280 degree camshaft if you want to go the whole hog. Plus there's the option of a Janspeed tubular exhaust manifold, or a stainless steel Mantzel item, should you so desire.
With regards the inlet manifold, despite what you may think it doesn't present a significant flow restriction on this application.
Please call us if you would like any additional info.
Bill Blydenstein :01763 272866 (just outside Buntingford Herts)
I'd recommend him, I've had 2 heads done by him and know of several others - all well pleased with the outcome. The last head i had done was the B++ conversion (larger inlet and zorst valves etc) on a 1.6 8v Nova engine running twin 40's which ended up pushing out around 150hp at the flywheel.
If you wanting to mod your induction but can't afford TB's try Velos 01283 542484 who do a sort of halfway house which gives a fair chunk of extra power.