Has anyone any experience of this Gravity manifold ?
The consensus is a 4-2-1 is better for more normal road use with more lower down torque than chasing high revs. It’s not badly priced either and obviously a remap would be beneficial.
Anybody fitted one of these ?
I’m going to guess not then… 
Could I be a bit of a pain though and ask that if you do end up fitting one of these to let us know what your impressions are? Eventually I’m hoping to end up with a fast road build rather than an outright track car, so torque over revs sounds like my happy place and I’d not heard about this 4-2-1 potential benefit before.
I would say the primary lengths are to short to be really effective.
Longer primaries, more torque…
I’ve used Gravity before, not for a manifold I admit.
I had a rear box for both a MK2.5 and more recently a NC.
Their products appear to be well manufactured and have always fitted oka, unlike some others that need ‘adjustments’.
Decent sound too, not to intrusive.
Hope that helps a bit?
Not really helpful being made in America and no outlet here unfortunately.
Well Davy, I did say it was an example of a good 4-2-1, not that it was available as it’s not made any more. However you can get a similar manifold made by Ryan Edwards Exhaust Fabrication (and plenty of others) who is in the UK!
Why has it got to be a 4-2-1 ?
Why not a 4-1 ?
Because as my first post alludes too…a 4-2-1 gives lower down power/torque gains against the 4-1 which is more beneficial in the higher rev range which I don’t want.
Well every day is a school day on the MX-5 owners club forum 
Another unfortunately……I don’t think my bank balance would like to pay for one of those bespoke manifolds that Ryan Edwards Exhaust Fabrication makes. Had a look at his website and he does fabulous creations, but bound to be very expensive.
To me those primaries look far too short. This will give profits though because the pre-cat will be gone.
My guess is you’re gonna be better off at low range revs with a decently designed 4-1 than a mediocre 4-2-1. I’ve bought an IL Motorsports as an affordable, on the eye decent design. And people have made nice gains with them. The header you quote really is at the bottom price-wise. That on itself doesn’t mean it’s bad. But the really short primaries plus no available experience and/or tuning + dyno results would put me off…save up a bit more and get something like the IL Motorsports one.
As the man quite pointedly pointed out to me…
“Because as my first post alludes too…a 4-2-1 gives lower down power/torque gains against the 4-1 which is more beneficial in the higher rev range which I don’t want.”
I’m of the opinion that a 4-1 will give him more torque but his digging has suggested otherwise…
When BLiNK Motorsport tuned my NC1, they fitted a 4-1 rather than a 4-2-1.
They told me that was the better option, I had no reason to doubt their word seeing as they were professionals in that field.
Go figure…
Just to add more info to the discussion. ( coming from a motorbike background )
Even different 4-2-1 headers can have different characteristics.
I noticed that the Gravity one first linked too has cylinders 1 and 2 linked - then 3 and 4 linked.
This typically gives a 4-1 style top end boost - although not as much as a full 4-1 header.
The JDL header linked too by BlueAgave has cylinders 1 and 4 linked - then 2 and 3 linked.
This typically gives the best lower down torque without losing too much of the top end.
@reggie747 - I wonder if they used a 4-1 because the variable inlet flaps help to boost low down torque and the headers give the top end.
Last time I have looked a “decent” manifold without a catalyst is around 450 quid and 650 for the one with a high flow catalyst.
are you saying that £450 is expensive or approximately 10 lb.ft gain at midrange is not enough with a lot more at the top end? (at least that’s my car stock engine full BBR exhaust with a high flow catalyst and tune)
You have to use the high revs on these engines anyway - honestly I’m not sure what the problem is.
