H&S 3" DP and Turbo Outlet Design Review
Done a lot of driving and running around this weekend so this has put me in a good position to give a “small”
review of the new exhaust and turbo outlet pipe.
Scope of the upgrade
I went for a full 3" Exhaust System for the following reasons.
1) Remove the restriction of the Miltek DP. The miltek DP is very good however the outlet of the downpipe is still stock and only goes to 2.5" once past the metal flexi part. This is fine for standard 150PDs and Hybrids however in the quest for more power going bigger is the only way. This also will set me up nicely for if and when I upgrade turbo.
2) Lower Exhaust Gas Temperatures! In the quest for more power its essential to keep the temps in check and with the older exhaust setup it was always in the back of my mind. If I want to do a long trip and track the car on the ring then I want lower EGTs for sure. 3" DP should flow more and thus reduce EGTs. Hopefully turbo will live longer too.
3) Lower noise. Ever since I got the new tip and the 3" piping to center silencer the exhaust was much louder than I liked. I some occasions it was nice to hear the wastegate chatter and the roar when accelerating. Other times I thought it was just too loud and not what the car was about. Knowing that 3" would increase noise I opted for 2 high flow silencers instead of one.
4) See if there are any performance improvements. the 17/22 Hybrids produce amazing results for the size of turbo they are. Some people say 2.5" is more than enough and even fewer say 3" DP improves anything at all.
Sound
When listening to the car on idle the exhaust note is now virtually non existing compared to before. The sound before was very hissy however now the hiss has gone. There is a burble especially now I added some miles and the car warms up but not a massive one. Inside the cabin however the engine note is now a lot lower but louder and it growls nicely when bliping the throttle. When driving normally there is a low gentle burble and definitely a lot lower noise than before. Changing gear there is not hint of a pigeon noise from the back either.
The exhaust really starts to open up at 3.5k. You get a lovely throaty sound but without the same high decibel roar I got before. It certainly makes the car feel grown up and expensive now.
Power
Squeezing the throttle you get power delivery that is now much more immediate. I would love the see the graph because it definitely feels like there is more power lower down. Definitely smoother power delivery and knowing that I said this many times I just can’t believe that there can be so much improvement from freeing up the exhaust. The power delivery was silky smooth before but now there is more torque availability lower down and it doesn't seem to tail off! The Miltek DP and centre silencer must have been more restrictive than I first thought. I am trying NOT to sound too enthusiastic about the difference as I am well aware that many of my previous performance mods made things more powerful and smoother. However I am beginning to wonder whether now I am at the limit of how smooth the power delivery can be with this turbo…seems too good to be true.
Past 3.5k that’s when things really begin to get interesting. It feels very much like a petrol in the sense that the power and sense of speed keep building as the revs climb. At 4K there still seems to be plenty of puff and the engine doesn’t sound as strained as before.
Playtime
As I stated before I had a little play with a new Porsche Carrera S within the speed limit of course (believe they are now 3.8ltr units instead of 3.6ltr and pushing an impressive 355bhp). I think the chap was a little shocked at what he found when he tried to stick on my bum when I first started to test the exhaust. Definitely felt confident in accelerating with the turbo outlet sorted and the new exhaust. I made a good account for myself and I think the fact he could over take me must have annoyed him no end.
Pros
+ Droning noise gone at 70mph
+ Great torque delivered more smoothly
+ Nice and quiet when driving normally.
+ Sounds grown up now and suits the car better
+ Definitely more performance. Might not be bhp but its added something!
Cons
- Expensive
- Got an annoying rattle because its so big. Can be sorted though
- Bang for buck may be lower in the grand scheme of things