Is there such a thing as the best of both worlds
 

Well as im sure you all remember a while back i posted what mods i was going to do to the exhaust system this year and after many phone calls with QTP reps for the butterfly exhaust valves and getting quotes together its looking like the system is going to cost me well over 2k, now am i beeing a total nutter in that i want the car to be silent like standard and then flick a switch and its loud ... its getting to the point where on a long run i miss the quiet because the drone form the system as its non resonating can be too much sometimes and i find myself driving over 2k rpm all the time in order to keep it quiet

Question .. Do i bother with the valves or shall i just quieten the Quads down and have a resonator fitted ?
or do i go all the way and have the expensive valves fitted ?

also what is the main difference between resonated and non resonated ? is there a major difference ? i love the sound but its hard to live with on a long jurney when i want to relax, or picking people up from the airport ect, motorways are fine because the revs are above 2k but these welsh roads are twisty and its a constant drone

please advise me before i go spending money and end up not happy +++

thanks Guy's

Resonated....
 

I had resonated and non-resonated pipes on my s4.....With non-resonated it was louder but u got the drone at 2000rpm especially in 6th gear....

With resonated it was quiet until I let rip and then the sound was amazing....I surprised what you want is so expensive....

yea i cant find anyone that makes the exhaust systems up themselves they are all generic boxes that are just ordered and installed on the car, i need someone that can understand that its a V8 and it needs a large box to keep things quiet all i have is two 4inch boxes and then the back box thats all, i could do with a nice centrer box to take away the drone in the low revs, do you know of anyone ? do unit 20 make there own or do they just deal with miltec

would it work if i installed the standard centre box back on and kept the rest from the back ok with the quads or is it the back box that takes away the drone ?

I don't know mate and i'm not sure how to work it out except trial and error.

its so hard living in the sticks when there is nothing around hear i have to travel a minimum of 80miles to get any fabrication done, im just wandering what makes the A8 or S8 so quiet is it the back box or the centre box that takes away the drone
?

How many cylinders fire in one revolution on the 4.2 ? im trying to work out the engine rpm x number of cylinders fireing in one revolution/60 or 2000 in order to work out the frequency witch will= the lenth of any resonators i put on, for example 133hz would be 2.25"x28" at any bend or shape so long as its capped

Surely it's a 4-stroke V8 engine so half (i.e. 4) fire on each revolution?
So at 1500rpm you get 6000/60 = 100 fired per second.

just spoke to mike and he is fairly sure the problem or rather the cure is to re-install the centre box as that contains the resonating chamber and hopefully that will solve my problem +++

Well its all done now its almost back to standard but of course i have kept the quads on there so there is no drone any more only a slight one very quiet again but when you give it some beans its a lovely V8 sound im in the middle of getting pipercross to make an induction kit for the S8 and A8 4.2 engine should be with me on tuesday or wednesday next week so i will report in with the result i think it will sound nice with a roar to it but the advantage is of course that you can keep it quiet when driving and after 4k rpm it will bring the engine to life a bit +++ thanks for all the advice on this