Hi mate,my o1 220 has holes for springs either side of the exhaust port ,and it has threaded holes like yours,when i bought it it had a standard exhaust on it push fit into the exhaust port and held on with 2 springs,ive now put a fmf gnarly on it and this is held on with springs aswell,on my 98 200 the barrel doesnt have any threaded holes.If your bike has been ridden so slow for a while theres a good chance everything is clogged up with oil and thats why its not going to good.Do some of the mods suggested on this forum and you will not regret your purchase :)