Top Gear exhaust & track days

Following on from previous thread about exhaust options and track days: http://911uk.com/viewtopic.php?t=147304 (as this is specifically about Top Gear & I know lots of members have experience of these). I called Top Gear yesterday and spoke to MD Steve Hill. He was very helpful. I explained I wanted to change my gundo-modded Dansk exhaust as it's borderline too loud for track days at ~105 dB. After talking to other people (also suggested on above thread), I asked him whether the mild silencers, 200 cell cats (cross over) and manifold would be ok for most track day noise levels. He confidently said 'yes, no problem'. He said this would also give a much freer flowing exhaust compared to my current set up, and the manifold is worth doing same time for long term peace of mind knowing whole exhaust system is good for many more years, giving optimum flow & adding a bit of extra sound without making it significantly louder. Does anyone else have experience of this TG set up & track days? Any issues with dB noise limits?

Glad to hear you have had this response from TG. I have done exactly the same thing as you (moving from Gundo to TG system mild+manifolds+200cell crossover cat). I haven't done a track day yet, but I can confirm the sound was significantly reduced (and improved in quality in my view).

I'm no expert here but i thought if changing the entire exhaust system to something like this .. which will certainly alter the exhaust gas throughput and back pressure then a Remap needs to be done ? need some info there as we are into modding and i always say that's outside of what i do . Please Bear in mind .. if changing exhaust manifolds then you are into possibly 12 snapped bolts and a drill out of each one .. the costs for that alone will soon mount up . Just pointing it out so it can be factored into the total cost

Thanks DeMort. You are totally correct as usual. The manifold bolts on my car will need some work to remove, although as I'm considering the engine work we discussed on Saturday it would also be ideal time to replace the whole exhaust system if I'm going down this path, especially as it would be remapped anyway. I just need to make sure I choose the right exhaust system for my needs. 'Project 996' continues after all your excellent work 😊

I run Porsche 997 X51 Manifolds and Top Gear Mild Sports rear boxes, when combined with 200 Cell Cats it fails on some trackdays. Run the standard cats and I have no issues. As such I run standard cats, I cant be doing with the agro that comes with failing the static, or having to short shift or lift and coast to beat the drive by. I have previous run Fabspeed sport back boxes and even with standard cats these failed the noise test at some circuits

I've run eBay headers, standard cats and top gear mild sport silencers at bedford and it was fine. However the same setup with decats was super loud (and not that good sounding, imo...) And I don't think it would have passed.

My 3.4 Carrera runs Top Gear manifolds, 200 cell 63mm X-pipe cats and the louder 'Sports" rear boxes. I think it sounds great though I've been told by a friend driving his 996 behind me that it is 'Bloody loud". I've never taken it on a track day but I think it's unlikely to pass a noise test (Sorry I can't be more specific!) I believe the mild boxes would be a lot more civilised with the more open cats. Adding the x-pipe a few months after the manifolds and boxes DID increase the sound level but also made the car feel much more 'Free revving" ie it never feels like it's struggling to breath at high rpm. I am looking into the possibility of modifying my old tail pipes (The very end pieces) with a pair of db killers so that (If all goes to plan) I can just swap out the 'Open" end pipes with quieter 'Track day" ones if needed. I'm sorry that isn't very specific to your question but I can say that the quality of the Top Gear is very very good, as confirmed by my specialist who fitted it having stated how well made it all was. I certainly recommend it anyway and don't find it excessively loud for road use but as I say, track day meters might have a different opinion.

Seems there's a lot of love of TG - just would be nice to know the noise levels of specific set ups, however seems like a try-and-see approach might be needed.

I get where you're coming from but I think the problem is always going to be getting your specifics measured. Manifolds or stock? Standard, 200 cell, 100 cell, x-pipe, 63mm x-pipe? Mild boxes or loud boxes? That's a lot of different iterations. Maybe you go a staged route. Fit the mild boxes, see how the sound levels are. Then fit the manifolds. Measure again and based on that (And how much noise 'Headroom" you have take the decision on the cats (Or not). Anyway, good luck with your journey!

Nice idea - that would definitely be a sensible thing to do, although I'm an in-for-a-penny-in-for-a-pound type of guy & get it all done at once, so will need to make a choice & hope it works 🤞

I had my 3.6 C4 with TG 200 cell X-pipe cats and the switchable boxes static tested at Castle Combe the other years. Only with the valves closed would I have got on track there. It was 97dB closed / 105dB open @5,000rpm.