Are you looking at making a shorty header, or more of a long tube design?

With or without cats in the system?

It seems that the long tube would be much easier to fit because you can get the primaries off the side of the engine and towards the underside of the car before you collect them. The collector and the pipes merging into it seem to be what make the headers so bulky. If you collect them under the car (long tube), you move the bulk into an area with more space.

The downside of this is that it wont bolt up to the stock catback, so everyone would have to purchase the headers AND catback to make it fit. Some people may want headers only.

SQ