Hi Gaz,
I have to agree with your friend, the standard exhaust system is very quiet and not, in my opinion, in keeping with the sporty nature of the car. I have a large bore stainless system on mine made by Phoenix obtained via Moss coupled to a large bore stainless sports manifold from Rimmers. It has a lovely burble on idle and rasp on acceleration and im very pleased.
To answer your questions:
<i><b>using more fuel - </b> </i> I have noticed no difference in fuel consumption at all, as the engine is allowed to breath more efficiently.
<i><b>my carbs will need setting up differently...... </b></i>yes, the best plan would be to help the way the car breaths in as well as out and replace the air box with K & N filters to complete the package. You will then need to run the richer 'BAL' grade metering needles in the carbs, obtainable everywhere and can be fitted in minutes. Tune and balance carbs as per normal.
<i><b>overheating??? -</b></i> the efficiency of removing hot gases from the engine is increased therefore making this LESS likely.
<i><b>will it affect power??? -</b></i> absolutley, thats half the point!!!
<i><b>and what ever else???What do you guy's think of it all - </b></i> personally speaking I think its an essential modification to me and an easy way of gaining a few more horses. A raspy exhaust note is great when blatting around the country lanes in summer and you will actively seek tunnels to drive through at full chat.[:D]
If building one from scratch insure that the primary tubes in the manifold are of equal length and have only very gradual and smooth contours. Stainless will last forever so thats a must if you are paying out for a custom build.
If you can why not try and twin exit system? After all the hangers are in place for the V8 system and it seems very effective on 4 cyl spitfires too.
My only word of warning relates to Triumphtune systems. John Clancy very kindly sent me the brochure for the Triumphtune manifold and exhaust made by Moss. Unfortunatley I had to wait 8 weeks for anyone to acknowledge my order at Moss and when it came, the exhaust system was as expected but the manifold was actually a Rimmers one but charged at Triumphtune prices. More frustrating for me given that I live 30 mins from Rimmers and could have collected it on day of order. I was eventually refunded the difference after I complained, but my advice would be to order direct from Rimmers or S and S Preparations and dont make the same mistake.
Wayne
Purple 2.0 Litre DHC Grinnal