hi mate
if its a mk1 hgt the decat is brill but not sure about the mk2, ive got the 20vt inlet plenum on mine as well as the turbo fuel rail and injectors these along with a FSE boost valve, full exhaust and air filter work really well together on mine the boost valve will get you some stick but trust me mate once set up you will understand why its worth the stick completely eradicates the flat spot in 3rd gear that the mk1 has, there is so much this engine can have done its unbelievable, it can be tuned to about 200bhp NA without nos it can be turbo'd and can be supercharged lol
get a set of denzo irridiun plugs (these work brill on this engine)
phone piper cams and ask for a price on re-profiling ure cams ((should be about £300 including postage) mine took about 2 weeks in total if i remember right.
get ureself a oil pressure and temp gauge so you don't fcuk the engine once tuned really lol
buy a vectra gsi or 20vt MAF sensor
give oil change frequently
get rid of the panel filter and buy an ITG cone filter and relocate it to where the old airbox is and the get a sheet of aluminum and close it off from the engine bay this is what mine will have when i have the money, at the minute i have a K&N which is a good filter itself but the ITG is the best air filter for the mk1 i believe i don't rate the BMC on it i think thats better on the mk2 from what ive been told
also the bore on the exhaust is ok to be increased slightly mine is the same thickness as the maf sensor this was done at custom pipes in balby with the new decat, also avanti motorsport do a gearbox for it that will defonatly increase acceleration it cost about £1300 all in but is worth every penny i had one on my old hgt and am having one for this hgt too ( the best mod you can do) get a oil breather slapped on but relocated to the opposite side of the bay than the filter, if you are feeling confident in ure ability you can also try these:
port and match the intake and exhaust manifolds re bore the throttle body to take out the narrowness of it before the butterfly but don't go near the butterfly
take the centre section between the head and inlet plenum off and bore these out and take all cast marks off
20vt inlet plenum on, this require quite a bit of fiddling to get the throttle cable set up and the empty holes on the plenum bunged up
avanti also do a super chip for the engine too
DASTEK unichip system to map ure engine to get the best from all ure mods
the timing can also be advanced or retarded apparently but dont know alot about this it was something i was told by avanti
get a custom manifold made up
use exhaust wrap an the exhaust
nitrous, id recommend wizards of nos like mine as they are probably the best kits about and good help too.
lol well thats just a few things you can do there is plenty more it just depends on what sort of car you want really and how much time and money ure willing to invest
calvert
