Outer Limits 4x4 Board

i have a 92 escudo 5dr auto with a 1600 g16a engine.
yesterday i fitted coby extractors and replaced the cat with a peice of straight pipe. (the original exhaust headers were cracked and cat was rattling).
since fitting them my truck is painfully slow below 2500rpm and not great above it!!
one thing i noticed was that the new extractors dont utilise the egr (exhaust recirculation), they simply block it off, will this make so much difference?
any help will be greatly appreciated as i dont want to go down the egr path (making up a new section of pipe from the new extractors into the egr) if theres an easier solution.
cheers
weemsy

an update and more information for this problem..........
i did a diagnostic check with the blink codes and got code 12--no fault!!
its a japanese import, incase it makes any difference.
i rplaced fuel filter, spark plugs, adjusted the ignition timing several times but all still the same.
any ideas?? anybody?? please!!
cheers
weemsy