So after getting a few quotes for around £250 odd to have the compression, timing and exhaust pressure checked I decided to just refit some standard bits and see what happened before spending money. I pulled the standard backbox out of the roof and quickly realised there was a good length of pipe missing from the centre silencer which must have been cut to fit the Supersprint rear silencer. So that was off the cards.

I then got the standard airbox/induction out, and managed to get it refitted after removing my catch tank.

I wasn't holding my breath but was genuinely surprised at the performance improvement. The dips/flatspots in power have gone and it pulls so much better. I emailed the guy that suggested the car might have faults to report this and he asked for a picture of the GSR. As soon as looked at it he said that it doesn't have a resonator on it like the standard one which can add power at certain points in the rev range.

So I'm happy that the car is running better now but it's just a pain in the arse to realise I've had the solution in storage all along, and have thought for years that it was the ECU not being able to cope with the mods.

Righty then, 1 year later.

When the standard intake went back on last year, there was a definite improvement. I had a little run out following the girlfriend in her Swift Sport thinking it would at least be level. No, the Swift pulled away still. Oh well "management" etc.

I did trackdays at Anglesey, Cadwell and Snetterton at the back end of 2018. Snetterton was the least enjoyable, big long straights and tight corners to lose all my momentum through. The only car I could pull slightly on there was a Toyota IQ so I got all miserable and locked it away for winter.

Get it back on the road this year and it just felt poor, below 4000rpm seem ok but then it was just flat all the way to redline. Went back to Cadwell, didn't go any quicker than 80mph all day and lost speed up the hills. I still enjoyed throwing it around in the tight bits but within a couple of weeks had it looked and and found that the throttle body was only opening ~65% of the way with the pedal down fully.

£20, second hand throttle body and a couple of hours cleaning and fitting it and the car is completely different! So when I said last year that putting the standard intake on was the "solution all along", no, a working throttle body is the solution! I'm assuming it has been faulty for years and either steadily got worse, or was completely useless all the time and I'd just never realised.

I have refitted a GSR and did seem to get a further improvement but to make sure I've booked an hour at a local rolling road to test as much of this as possible with what is already on the car (Supersprint manifold and rear silencer):

Standard intake + paper filter
Standard intake + performance filter (although this one is probably not going to happen as I've found that the filter is damaged and might not seal 100%)
Standard intake pipe + a chopped up GSR Induction kit in place of the air box
Full GSR Induction kit

Once that's settled with figures I plan to refit the Supersprint front/centre pipe (with sports cat) and go back to the rolling road and see what happens again.

I've had another little run out with the Swift and was pulling away from it, not a massive amount but it's a nice change. I'm going back to Cadwell next month to actually enjoy the car properly! Managed to get to Curborough the day after I fixed it and it was much better around there.

Had it on a rolling road last Tuesday and tested different induction setups. These are all with a Supersprint manifold and rear silencer fitted, and the gauze removed from the throttle body (trying to squeeze every last pony out).

Run 1 - Standard Induction - 135bhp
Run 2 - Standard Induction with Jetex drop in filter - 136bhp
Run 3 - Standard Induction hose/chopped up GSR Induction kit hybrid with Jetex angled filter - 142bhp
Run 4 - GSR Induction kit with Jetex angled filter - 141bhp

Run 4 setup made more power lower down than the run 3 setup and then they switched over higher up the revs. The guy there recommended running the Run 4 setup for that bit extra low down.

I made the mistake of asking for the graphs to be emailed over rather than printed and still haven't had anything so need to start hassling. As far as I can remember there was a ~5 lb-ft increase with the induction kit and hybrid.

Over the weekend I had a play with some more silicone and manage to extend the GSR so that the filter was sat right behind the bumper opening. After driving it for a bit yesterday I thought it had reduced the power lower down the revs so switched back to how it was on Run 4 for the time being. The differences will be so small here that the only way to know for sure will be on the dyno.
I think I can improve the extension setup slightly (get rid of one joint) then will head back to the rolling road to try it along with the one piece front/centre/sports cat exhaust piece I have.

Another idea I've got is to make up an airbox/enclosure for the filter which should be fairly simple to do.