Hmm, now that is an idea PGT. Likely a little louder than my present RMW street plus JCW, but not by a whole lot I suppose. And yes on the tips, they make a huge difference in the look. Those 1.75" tailpipes are just plain naked with no tips.
A 1.6 liter motor can only push about 396 cubic feet per minute max at 7000rpm hot air if the head and header are designed to handle that. The common idea of ok its out of the header now I can go big get some growl and not worry about the exhaust velocity falling off really sells the rest of the system short. Yes you want to gradually step up size as temps drop (where you want your power determines where you step) but just going massive after the cat isn't the best. Plus people like me can then use the stock tips and really mess with people's heads.
I hadn't really concidered the JCW, I wanted to try and make something of my own that would use a minimum amount of components placed as near the center of the vehicle as possible (ie not having the mufflers at the very back of the system). I figure that the weight loss from such an exhaust would be more beneficial than whatever small power-gains it gives me. Weight wise how does the JCW compare to others, is there a comparison of it and others somewhere?
I'm in the same boat, I want to save a few pounds on exhaust but yet have added 10-20lbs of subs and amps to my car. The coilovers/R56 trailing arms and lighter suspension parts are on the wish list but money for an exhaust is more likely available sooner. My idea (in my head) was to shave the battery-box down (similar to how you did) and placing a resonator shortly after the cat with a decent muffler located a bit farther downstream (but ahead of the rear-wheel centerline if possible). I'd also thought of eliminating the exhaust opening in the rear valance and having it make a 45 degree downward angle and exit more towards the middle of the car thinking maybe doing this would make the exhaust sound more muffled (that or the sound would resonate off the road and underside of the car and sound louder). I'd really have to play around with it.
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