I'm trying to identify the differences in exhausts between the "normal" S3 NA cars and the very last ones produced with the HC NA engines prior to the introduction of the X180, as I'd like to finally replace my leaky and wonky SJ setup with something from Alunox. I still have the original cast HC manifold in the garage I can check and/or send to Alunox for measuring, but sadly don't have the rest of the original system.

Having spent hours looking at the parts diagrams, workshop manuals, many previous posts on here and pictures from various suppliers/websites, it looks like:

1.) the original HC NA manifold was identical in terms of mating to the engine, but the 3 stud mounting flange/connection to the downpipe for some reason was reversed compared to the "normal" NA cars.

2.) The original HC downpipe has a "hot air shroud". I'm not sure what that does or if it connects to anything else, and the current SJ tubular setup fitted to my car doesn't have such a thing, so not sure it's needed...? Having carefully compared the "normal" and HC downpipe images from various suppliers, it looks like other than the expected "hot air shroud" addition and the reversed mounting flange the pipes are the same dimensions and follow exactly the same route?

3.) The mid pipe and rear box are identical between S3 NA and (S3) HC NA cars.

So if I'm replacing the entire system from manifold to back box, am I right in thinking a standard S3 NA setup from Alunox would fit fine given I don't need it to mate with any original HC parts of the exhaust system, and there's no chassis changes that mean it will foul on something?

Thanks,

Paul

Paul, what about the full system from lotusbits, they are tuned (lenght) to give more mid range? 

Sorry, I didn't get a notification of your response for some reason!

My understanding was Lotus Bits only do a single exit tail pipe for their system, which may help performance, but I'd prefer to keep the original look. Also on the group buy the Alunox prices are very attractive :-).

The Alunox manifold should be optimal for our cars given the 4-2-1 primary/secondary pipe configuration.