Neal, the header pipes are 1.75 inch diameter, the tail pipes are tapered. A special baffled insert is fitted internally for road use, otherwise they are removable and its all noise !
Hi Trond,
I got a set when I was in the U.S from Speedwaymotors.com. They do the Megaphone end pipes in chrome or non coated steel and in two lengths.
Try this link Speedway Motors - Product Summary
I have just put these onto my car. The megaphones were 2 inches at the small end and 4 inches at the big end. I think in reality 4 inches is a bit big but the other options were too small. Remember these are off the shelf items not cutom expensive pipes. But the quality of welding and material thickness is very good. We trimmed the small end to match a pair of collectors and to reduce the over all length to what suited the car and still able to open the rear deck. At present they are not yet coated but will be when I send off my other exhaust sytem at the same time. Mick Sollis at Southern GT supplied my collectors. I got the link for the megaphones from another thread here on the forum but this morning haven't been able to find it. It wasn't Burns Stainless though and they cost a huge $50 a pair! We got 4 sets back to the UK for about £150 via hand luggage!
The noise is outrageously glorious! Quite a different sound to running just primary pipes. Not that there are many places where you can run them in the UK but we have found a track day at Donnington in September where we plan to run them.
This picture is one where we just pushed the system all together and is nowhere near the finished article but is the only picture I currently have at the right size for Forum posting. Now they are properly aligned and welded up with Lambda bosses included. About £250 all in.