What does the Irish test actually test for?
In UK, MOT only does a smoke test at high revs. My de-flapped, EGR-blanked, and Stage1-mapped 147 Sport Q2 passes that at 50-55% of the permitted limit - an easy fast pass.
Lack of flaps will somewhat increase HC (unburned hydrocarbons/fuel) emissions at low revs. Blanked EGR will increase NOx somewhat at low revs. Above about 2,000 rpm neither flaps nor EGR are playing any part in emissions. EGR is closed and flaps are opened, by the ECU. Neither CO/CO2 are tested but DPF (not on UK 147's) and catalysts are inspected.
It's not impossible to use earlier CF2 or CF3 all-aluminium manifolds which never had flaps, or had the plastic flaps now plugged or welded up. But you'll have to figure out some way of mounting and connecting your original CF4 swirl flap motor. On CF3, the motor was different, and mounted differently. I don't know about electrical connectors and ECU values. Might be easy, might not. Your CF4 swirl flap motor has to stay electrically connected so the ECU thinks its there and working correctly. There's no method of mapping it out and binning it.
IMO de-flapping your existing CF4 manifold is just easier. The actual manifold containing the flaps of doom is just a short aluminium stub, the plenum chamber is black plastic. Those parts are held together by just 3 screws, down the back. That makes the CF4 manifold much easier to remove and replace. Take off the plenum, then remove the nuts and studs on the manifold. The swirl flap motor is mounted to the underneath of the manifold and operates the swirl flaps via a rack and pinion. You just unbolt the motor, remove the plastic cover on the underside of the manifold, lift the rack and pinion out, and replace the cover, then re-mount the motor. Externally it's all stock.
It's also easy to de-flap your existing manifold, using a bit of violence to remove the flaps and spindles. There's no requirement for plug kits or welding. Just tap threads into the old spindle holes, then screw in short bolts that don't protrude into the inlet tracts.
Refitting is the opposite. Don't forget to reconnect the Red-Brown loom connector to the motor (impossible once installed), being especially careful
not to connect the identical-but-Grey EGR connector instead (which I of course did, meaning I had to take the manifold off again). Then replace the manifold, then studs, then nuts, then plastic plenum and screws.
Far the worst bit is cleaning out the interior of the plastic plenum, which will be coated in a thick engine-strangling layer of soot and oil. Most solvents barely touch this filth. I eventually used that ferocious oven cleaner supermarkets sell, which comes in an orange box, with a large plastic bag and gloves. It still needed a good 48hrs of soaking (in the bag), with frequent agitation, and was probably the messiest, nastiest job I've ever done this side of drain cleaning.
CF4 stub manifold with swirl flap motor. And missing flaps on #2 and #3 - eaten by the engine, and those repairs were a
much bigger job.
The rack and pinion whereby the motor rotates the spindles is beneath the flat black cover.
BTW don't do as I did and remove the end cover of the motor. There is no need and eels live there which
will escape and be tricky to replace.
One of the swirl flap spindle holes, after drilling to 7.1mm and tapping to M8... the manifold alloy is really soft.
M6x1.25 x 18mm bolts Loctited in place. The heads have to fit under the plastic cover (not shown), which would keep them in place if they began to back out - but mine have been fine for 7 years now. You can see the remains of the rack and pinion, the little central toothed pinion that the motor drives. The rack was junked.
The horrible appearance of the alloy was my fault, it reacted badly to oven cleaner. I ended up rubbing down and spraying it metallic silver.
Good luck!
