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True dual exhaust causing bad clunk - thinking of going to single pipe like loudmouth
Hi guys,
Ive been having a serious thud and clunk coming from the back end of my 01 WS6 A4 which i thought was suspension related or diff related. Turns out, my super duper true dual exhaust which was fitted by a previous owner is not so super duper at all. The way its been designed and made is poor. The 2 pipes go down their respective sides of the car unlike most true dual setups i see on these cars. The drivers side over the axle is where the problem is. Its hitting everywhere. Hitting the axle tube, the floor pan above the axle, the panhard rod and so on. If i go over a large bump or pot hole, the axle hits the pipe and pushes it into the floor pan. I don't know how I've missed this before with all of the searching i did for the source of the noise. It was only when i got it up on a 2 poster lift that i could see all the damage to the exhaust pipe and axle tube.
Anyway, I've been to a few exhaust shops and all of them are saying the same - the way its been made and the room available means they can't fix this problem without starting fresh. Ive shown them true dual designs such as TSP and the Hooker Blackhearts system but non of them are willing to give making a similar system a go. For me to get one from the USA will cost me around $1500 delivered with taxes paid and then ill still need to pay somebody to fit it. Im not willing to spend that much on an exhaust system. (will be around $1800 all in so £1400)
As the car was tuned with the true duals and x pipe, will going back to say an SLP loudmouth 2 drastically alter the way my engine runs? will i need a retune and will i be looking at dropping major horsepower and torque?
The mods i have are:
XER281HR cam
Fast 92
Fast fuel rails,
Injectors - can't remember the flow rate but higher than stock
UMI Throttle body
SLP lid and K&N filter
Forged H beam rods and pistons on a standard displacement
Comp trunions and roller rockers
Melling high flow oil pump
Pacesetter S/S headers
De-cat
True dual exhaust in 2.5inch with x pipe to magnaflow dual/dual muffler
PCM tuned by a UK LS specialist.
Yes I understand that this is the case. I've been to local custom exhaust shops and showed them images of the TSP/Kooks and Hooker true dual system to see if they could fabricate one for me but most of them either said they won't do it as they feel two pipes over the axle above the upper panhard support is too tight or too much work for them. To get one of these USA made systems to my door in the UK and then get it fitted will cost me about £1400 or $1800!!
Why not go with a dual system dumped before the rear axle? Just cut off the current over the axle pipes and install a bullet muffler on each side? Just a thought to save money.
As for dumping before the axle, I would likely run into problems at the MOT test (our version of an inspection) as we aren't allowed to have exhaust gas exiting under the floor or boot/trunk of the car as they class it as giving rise to the risk of exhaust gas entering the passenger compartment.
Under the axle seems good, ive not seen one like that before on a 4th gen.
Friday morning I will see what the custom shop says about this idea!
So just a thought. I have a custom 3 inch y into a 4 inch dynamax single dumped before axle. Like u i had the same issue where my state requires exhaust to exit away from vehicle either the side or out the back. So i had the exhaust company hook me up. What they did was after the y, the 4 inch muffler is not welded but banded to the y. They made a single out the back setup that i slip on for inspection. Has an ugly 4 inch to 2.5 inch reducer on it, but slap that on and u will be able to pass. Then take it back off.
You can buy a welder and stainless pipe for cheaper than a bolt on kit. I made my own 3.5" single pipe and picked up about 14rwhp over some crappy true duals, and it definitley needed a tune, it was pinging on hard accel after the change, my tuner couldn't believe that was the only change.
Ive found somebody who is a one man operation who has agreed to make me the true dual - he says its not a problem for him. Going with 2.5 inch duals, X pipe and bullet style mufflers with dual outlets each side.
Very reasonable price as well at less than what would be $750 in the states.
Ill post up some pics and sounds once its done! - going in to be done a week on Monday.
07-10-2017, 07:41 AM
True dual exhaust causing bad clunk - thinking of going to single pipe like loudmouth 
