What is the best cost effective upgrade for more low down torque/power ?.

Only mods at present are a centre section decatted exhaust and Group N rear box and an STi air filter.

Car is used for hillclimbs and the handling is sorted with adjustable dampers, uprated springs, Whiteline front & rear ARB's, Whiteline front & rear droplinks Whiteline anti-lift kit and slicks but I need some more torque/power.

Total decat with downpipe must be next (c20bhp), AP racing cluctch (and possible flywheel) but any other suggestions ?.

 

ive heard that equal legth manifolds add tons of torque, but you loose the warble and they're not cheap either

 

You dont say what car you have but assuming post 99 turbo then a Bob Rawle TEK3 will sort your problem out nicely.

 

what MY??

 

Don't touch any exhaust manifold, you did gain some more torque but spool up point is ALWAYS increased and this is so important in your case, believe me I use my car in similar situations and only full decat with a good remap as suggested could give you instant throttle response and driveability.
If you upgrade your I/C and hood scoop with say STI I/C etc along with turbo and I/C inlet hoses you have much better spool up and torque.
JIM