New Performance Exhaust & Resonating Dreadfulness
Discussion
Three weeks ago I had a new performance exhaust fitted by M.I.J. Performance in Walsall to my Mercedes-Benz SLK350 (R171 2004), all nicely done in stainless-steel.
My aim and desire: Improved performance and a more 'sports' exhaust note, as compared to the mooing of cows that the original equipment pipes produced. I had the engine re-mapped at the same time. The intended outcome was a 'mid-sports exhaust note' and improved performance.
The enhanced performance is indeed superb, more responsive, faster acceleration, pulls better and I'm very pleased with it.
The exhaust note is good too, with the roof down that is; BUT... with the roof up, at around 2000 r.p.m, I get a bloody awful loud droning resonance inside the car, it is actually very, very wearing and very tiring. At one precise sweet spot of pain in the power band; 2100 r.p.m., when the engine is pulling under load, the resonating actually achieves a high pitched vibration that sets any loose bits in the car rattling, including my fillings, my testicles, my eyeballs and brain. SWMBO, on exposure to this penetrating drone sat in the passenger seat for long periods of a 2 x 2hours of drive with her fingers in her ears, taking them out only occasionally to berate me. She didn't actually say "You've ruined a perfectly good car" but she could have and I wouldn't have disagreed.
When I troubled the very helpful man at M.I.J. with this issue he said to leave it for a thousand miles and when the new tubes coke up a bit the sound will mellow. I'm up to over five hundred and it's no better. He also said that should the need arise it'd be no problem to moderate the exhaust.
Now, my quandry is this: It's three hundred mile round trip from home to M.I.J. so I can't keep popping back, I want to get the thing modified in one go and I want it done to my satisfaction. What I want is to keep the extra horses and torques, retain something of an exhaust note at the tail pipe, if I can, but above all, I simply must be rid of this resonating racket in the cabin - anybody have any sensible advice on what's best to do in order to achieve this?
By the way, the new pipes are straight through with silencer boxes at the back - I think the O.E. version has a little boxes half way along the pipe? Is this significant? (I think it might be)
Thank you.
My aim and desire: Improved performance and a more 'sports' exhaust note, as compared to the mooing of cows that the original equipment pipes produced. I had the engine re-mapped at the same time. The intended outcome was a 'mid-sports exhaust note' and improved performance.
The enhanced performance is indeed superb, more responsive, faster acceleration, pulls better and I'm very pleased with it.
The exhaust note is good too, with the roof down that is; BUT... with the roof up, at around 2000 r.p.m, I get a bloody awful loud droning resonance inside the car, it is actually very, very wearing and very tiring. At one precise sweet spot of pain in the power band; 2100 r.p.m., when the engine is pulling under load, the resonating actually achieves a high pitched vibration that sets any loose bits in the car rattling, including my fillings, my testicles, my eyeballs and brain. SWMBO, on exposure to this penetrating drone sat in the passenger seat for long periods of a 2 x 2hours of drive with her fingers in her ears, taking them out only occasionally to berate me. She didn't actually say "You've ruined a perfectly good car" but she could have and I wouldn't have disagreed.
When I troubled the very helpful man at M.I.J. with this issue he said to leave it for a thousand miles and when the new tubes coke up a bit the sound will mellow. I'm up to over five hundred and it's no better. He also said that should the need arise it'd be no problem to moderate the exhaust.
Now, my quandry is this: It's three hundred mile round trip from home to M.I.J. so I can't keep popping back, I want to get the thing modified in one go and I want it done to my satisfaction. What I want is to keep the extra horses and torques, retain something of an exhaust note at the tail pipe, if I can, but above all, I simply must be rid of this resonating racket in the cabin - anybody have any sensible advice on what's best to do in order to achieve this?
By the way, the new pipes are straight through with silencer boxes at the back - I think the O.E. version has a little boxes half way along the pipe? Is this significant? (I think it might be)
Thank you.
I made the 200 mile trip up to MIJ again this morning.
It transpired that the geezer who fabricated/fitted my exhaust didn't comply with his instructions and put on silencer end boxes that were smaller than specified.Hence;too much noise and resonance.
Much genuine apologising for the error ensued, then more apologies when it further transpired that they didn't have the requisite size back end boxes in stock; they'll have to be ordered.
So, I have another 400 mile round trip to look forward to and another Saturday used up to visit MIJ again for remedial work. On the plus side the man who runs the show (Andrew) said they'd reimburse me for petrol money, which I thought was fair enough.
I'll let you know how it all eventually pans out.
It transpired that the geezer who fabricated/fitted my exhaust didn't comply with his instructions and put on silencer end boxes that were smaller than specified.Hence;too much noise and resonance.
Much genuine apologising for the error ensued, then more apologies when it further transpired that they didn't have the requisite size back end boxes in stock; they'll have to be ordered.
So, I have another 400 mile round trip to look forward to and another Saturday used up to visit MIJ again for remedial work. On the plus side the man who runs the show (Andrew) said they'd reimburse me for petrol money, which I thought was fair enough.
I'll let you know how it all eventually pans out.
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