I'm just in the process of fitting Siamese pipes to a 1970 (non OIF) Lighting. The old twin ballenced pipes were held rock solid by the ballence pipe and the Frame tab fixing bolts.
The Siamese pipes I bought have lugs welded near the head, that accept a tie bar (not surpplied). I expect the tie bar arrangement and the bolted frame tab will offer a similar stable fixing. I can't see free fitting pipes, until they meet the silencer, being as stable ?
A quick question...... should any exhaust jionting compound be used in the head ports, if so which type?