From Sands interview:
Is the engine so highly tuned that any modifications will not help?*
Yes, to a certain extent. For example, Lotus will offer three levels of exhaust, each progressively lighter and louder. They cannot ship the louder exhaust on the car as the car must meet strict sound regulations, especially in Europe. However, once the car is delivered, and depending on the state, the owner can fit a different exhaust.
It will be extremely difficult for after market companies to offer an exhaust with the same performance level as the one offered by Lotus. The exhaust tube is bifurcated at a specific distance from the header. This distance is critical and if not duplicated, power will be reduced.
Arno: I hate to say it but you are probably not quite right when it comes to the exhaust making any hp. Take a look at the boxster situation. There are probably 15 different exhausts available for it, yet only 2 dont lose a measurable amount of hp. None of them boost it. The 2 "winners" are the porsche sports exhaust, and the GHL 5" exhaust, one of which is outrageously expensive, and the other is very very loud (110db measured, c-weighted at the drivers head level 2.5k-3krpm). Tests were performed on a dyno and you can ask anyone about it over at ppbb.com.
While I don't doubt that a third party company will be able to *match* the stock lotus exhaust, my guess is it will A: take a long time B: not be the rule C: be very expensive. Remember, we are not talking about some long long tube with a ton of radical bends, flat sections, and poor manufacturing qualities. Midengined cars have a big advantage in that they can generally be optimally designed right from the getgo. There is no passenger compartment to get around, no underbody travel height restrictions, no tight bends. Just a straight shot out the back of the car. They add in a few bends to make the length proper, put in a cat or 2 and add a big old muffler to kill sound but not performance and bingo, perfection. Reduring backpressure does NOT mean you are going to gain hp. It might, but it is definitely not the rule.
My guess is you are right about the modification part, until the cams change and the headers go on, the exhaust will not be a place of much in the way of hp gains.
(Of course, this being a toyota and a lotus, those cams and headers should be changing fairly quickly IMO )
Hmmmm interesting thread. I must be a poser, because I want to lose no HP, but have a louder sound. I don't want this thing to sound like a Camry. I realize the winding it through the powerband and keeping it in V V range will make it scream, but I'd like to make a roar at 3-4000 RPM too. I hope my dealer can help me out, but I'm not confident.
NE1 know if the lightest and loudest will be titanium? I might buy it just for the weight savings. Initially I'll be in the Tony Shute mode of trying to put the Elise on a diet. I'm also considering a race day battery and a racing alternator each of which weighs 50% of there counterparts. I'd also love to get a hold of a set of metal matrix rotors like on the original Elise. The rotors alone shaved 26lbs and that is unsprung weight!!! I'm going to buy a pair of superlight weight track wheels eventually. I'd love to get the Fed S2 (1978lbs) below 1900lbs and retain the AC. 100lbs of weight savings, that is my holy grail.
I can't help it. It's in my nature. I used to bicycle competitively and we counted every gram. I'd have paid $1/gm to lighten my bike. Another benefit is handling. Most of the weight loss will happen in the rear improving the weight distribution. Any thing to achieve more neutral handling.