Audi RS2 - exhaust cat-back recommendations

[JonRS2]

Hi Kit, I have not heard the exhaust note (or the engine) yet since the reconditioning. The car has been on a ramp for months. I should be driving it next week for the first time in 2 years and 4 months, and will report back after that. It has been a long saga but it now has an MOT (driven there and back by the garage) and is no longer SORN.

[JonRS2]

28 miles driven today in the RS2. Mainly low speed and at no more than 60mph (I was delivering it for its next appointment).

First impressions of the new Supersprint cat-back exhaust:

* It sounds much sportier and makes it seem like the car is accelerating / going faster than it probably is (or than it seemed when the cat-back part of the original Audi long-life exhaust was on the car).

* It is definitely louder (and somewhat louder than I had hoped it would be, but certainly not unbearable). It is as if I can hear the engine a lot more?

* The note appears deep and throaty to me, but I cannot draw on other examples (e.g. Jetex) for comparison.

* No bangs, cracks or pops (thankfully). No droning as such on this first drive, but there was some loud resonance on a few occasions - mainly when accelerating in second gear from a very low speed. I would prefer it didn't do that, but it does - or at least, it did on this journey.

Overall, I would say it is very different to when the cat-back part of original Audi long-life exhaust was on the car. In some ways, I think it is an improvement. In other ways, I prefer the almost silence of the original.

I wonder whether the sound will change over time, and how it will sound at motorway speeds.

By far the biggest improvement is in the feel of the car after reconditioning the front and rear sub-frames and suspension and fitting new rubber bushes throughout, new springs front and rear, new Bilstein B8 rear shock-absorbers, new brake discs, pads, shims, reconditioned brake calipers, four new tyres on refurbished wheels, 4-wheel alignment, etc., etc. The ride was not harsh at all. It felt perfect to me. Precise.

A couple of annoying new issues have now manifest themselves, but hopefully they will be resolved in the next couple of months.

[K Simmonds]

Glad to hear you've been able to get to drive the car after obviously investing a lot of money into the old girl and that it's driving nicely, congratulations for keeping one of these car's in such good order...

Thanks very much for the highly detailed feedback regarding the Cat back Superprint system, as I mentioned the system I fitted over ten years ago now was the complete turbo back job with just one single pipe/joint and a built in sports cat. I found that to be a lot less loud than Cat back Milteck's, I've never actually heard a complete Cat back Jetex system on an S2 or RS2 so can't comment on how that compare's. Though I've had them on a Corrado G60 and a couple of MK2 GTI's and they were quite a bit louder than stock but not excessively so. But comparing that to a turbocharged car is fairly pointless as the charger itself make's the exhaust considerably less noisy, plus they're different car's altogether.

However, I did use a 2.75" Jetex backbox on my otherwise 3" straight piped RS2 spec 3B and was surprised by how quiet it was, sure it was loads more noisy than the the stock system I removed but not what I'd call offensively loud. I did have to live with a slight drone at legal motorway speed's but that would have been due to having no Cat's or any other boxes not the the backbox itself. I didn't get any pop's or bangs either and that car was mapped very aggressively indeed for uprated rod's so it was really chucking the fuel in with an often sub 10.5 AFR on WOT.

Pop's and bangs come from unburnt fuel igniting in the exhaust system and road car's generally have to be mapped specifically to make this happen which is pet hate of mine, I can't stand what's referred to as 'crack map's'. Racing engines or very highly tuned cars are a different deal altogether mainly due to the the cam timing being a compromise between being able to make the car start from cold then tick over warm and outright performance.

I doubt the car is putting out anymore power, well certainly not enough to notice anyway on a car that's already very fast unless one of the previous OE boxes had started to collapse inside which is highly improbable. I've seen a couple of collapsed Cat's before but never one of the boxes on an Audi of this era, they're simply too well made.

However the Supersprint is less restrictive than the stock system so it may be just a touch more powerful and more importantly free revving giving the feel that the car is more powerful. The car I fitted the complete system to ran a touch over 320bhp on the dyno at VRS, though there was approximately 30NM more peak torque compared to the owners other RS2 ran on the same dyno under the very much the same atmospheric conditions. That car just happened to put out bang 315bhp with a little more torque than than stock, both cars were still running stock software.. However dyno's are tool's for tuning not definitive performance figures there can be a huge difference between machines and numerous other variables. One can only accurately compare data collected on the same machine, day and opperators.

to make any serious difference to performance the car really needs the complete system as well as remapping to make the most of it.

The one I fitted was had a nice deep tone, yes a bit more throaty than stock will zero drone or resonance but not what I'd call very loud. I like to able to hear what an engine is doing, I had no stereo in my old 3B for this reason as well as to save a tiny amount more weight and I always turn the radio off in any car if doing some serious driving. In fact I very rarely ever listen to the radio in at all these days apart from on long journeys or when stationary.

I can only assume the resonance is due to retaining the twin cat set up and is probably something to do with the post Cat Y arrangement and adapter as opposed to the boxes. It may change a little once you've gotten a decent number of miles under your belt but that will probably be something you have to live with.

Unless I can find a second hand Superspint system for sane money (fat chance) I intend of using a Jetex Cat back set up but with decat pipes making a compassion pretty useless as Cat's greatly effect the exhaust note. I would rather a Supersprint but feel the money would be better spent on more important things like getting the turbo rebuilt as well as a host of other jobs required.

[JonRS2]

Thank you, Kit

One thing I forgot to mention: while my RS2 is almost completely stock (other than the new Supersprint exhaust cat-back), with "little red" brakes, and parts have whenever possible only been replaced with original Audi or Porsche parts (or, for example, replacement of Boge shocks with Bilstein B6 at the front and Bilstein B8 at the rear), my RS2 does have a stage 1 remap (on the road with/by Mihnea of MRC back in February 2009). It has never been on a dyno but, at the time it was remapped (and it has only been remapped once, not since then), I think I was told it would likely be up to 360 bhp and 500nm (370 lb/ft) torque (up from 315 bhp and 410nm (302 lb/ft) torque). But I may have misheard or misremembered the figures, or they may just be optimistic. With age my RS2 may be achieving less than those figures now?