I replaced the complete exhaust on my 2005 JCW with a new catted header and cat back from eBay. The car is my winter daily driver so didn't want to spend too much on it. Still way too loud and too much resonance for me. I'm considering a used S exhaust. Was there much performance difference between the S vs JCW exhaust? I assume it'll be significantly quieter than what I have now.

 

Along the same lines, I have an 2005 S that I've only driven about 500' from my neighbors house to mine. I was going to do the "one ball mod" to mine. Is the "noise" from that objectionable?

Winger,
I hope this isn't a hijack of your question, but I thought the answer might be helpful to you as well in making your decision.

Basically from a hot rodding standpoint, less back pressure is helpful in producing power. But at the same time, the upstream restrictions have to be in sync, ie; less restrictive intake, bigger cam etc... Too little back pressure can make the engine run too lean to where the injectors can't keep up with the mixture.
I'm doing a 15% pulley, cold air intake and the one ball mod, along with colder plugs. Mild alterations to be sure, but hopefully in "balance".
robj
robj

 

Yes, as noted, any engine, even more an "S", and even more than that, a JCW engine greatly benefits from free flowing exhaust and the ECM mapping to go with it.

Winger -
If you "plug" up your JCW engine with a "stock" exhaust system, the likelihood of it running rich is very high. Installing a JCW exhaust system is your best bet, for a combination of noise and the engine running well.

Mike

 

Thanks. Was wondering if anyone did any dyno testing before and after the S exhaust vs JCW but I haven't found any. I also assume the exhaust mounting points are the same.

 

I'm running a 15% pulley and one-ball exhaust on my '04 S. I will note that I already had a Dinan Stage 1 tune which bumped the initial factory 163hp to 175hp prior to the pulley. I estimate that I'm now running around 195hp with the pulley and exhaust mods. You can hear a difference post-one-ball but it's not at all loud or annoying. Plus, you drop approx. 30lbs. and gain approx 2hp! I will say that these two simple changes created a huge boost in performance. I do have 380cc injectors to install (needs a re-tune) but I don't anticipate that doing much for performance since my main objective is switching from 2-port MINI to 4-port Volvo injectors for idling consistency.

 

Tell me more about this Volvo injector trick!

 

BTW, 380cc is the same injector size as the JCW. I purchased four (4) Bosch injectors used by Volvo that are a direct replacement for a MINI. FCP Euro was the source and the SKU Label # is BOS-62722. If I remember correctly, they were right at $100 for the set of 4. You will also need to purchase MINI o-rings ($6) since the Volvo o-rings that come on the injectors are a bit too small. EV6 to EV1 male F1 electrical connectors are also required and are around $15 (set of 4) on eBay. As I mentioned, the Volvo injectors are four-port instead of two and should provide a much smoother idle since fuel atomization is better. Downside is they also require an ECU tune (on/off cycle modification), otherwise they'll run rich on an S. There's a remote tuner/auto engineer on this forum (name: adriancl) that you can PM for details (he's very reasonable, works via email and only charges if you're satisfied. Tell him I referred you.). If you search the forum I'm sure you can find additional information on this injector mod. I've yet to install my injectors because I'm waiting until after I replace the timing chain/guides which should happen in the next week or two. Good luck and post your results if you decide to do it.