Ok, so all finished with the testing!
There was a slight delay as the autodelta intake was second hand and well used, so I had to silicon bond around the recieving rubber pipes to ensure an airtight fit.
All of the following is subjective but I`ve tried to be honest with myself
Removal of the intake Trumpet:
The advantage is a full 80mm 'mouth' for the air filter box, so increased air input and air is collected from lower down so its less suceptable to engine heat (it gets a better air feed from the front grill too). Potential disadvantage is water ingress to the filter box if traveling through high water, although it would have to be quite high! Driving through heavy rain caused no problems for me as the area just doesn`t seem to get wet even though I checked frequently. If you are worried you could add an 80mm pipe to route the intake higher up whilst still keeping the better flow. It gives a louder throb/roar to the engine at full throttle and seems to allow faster acceleration at higher revs (5K+).
Addition of an Autodelta intake:
No louder at part throttle but a HUGE roar when flooring the pedal - almost too loud! Throttle resonse is better and the car really wants to pull (wot, more
). The normal 4K Revs point for a stepped increase in power output has gone but extra power is now streched out in the full 2.5K to 6.5K rev range
. Lower revs are much smoother and faster to get through and the problem is now trying not to red-line it all the time as the deep note makes you think you are at lower revs than you are. I would be interested if other AD users had noticed quite such a loud noise. Incredibly worthwhile mod
The Autodelta intake differs form the original in that it is the full 80mm diameter along its full lenth. It also has no resonators. It follows the original intake shape precisely.
The original intake changes from 80mm to 80x60 (approx) when it turns horizontal, in part to accomodate the lower resonater. This is clearly restrictive to the flow.
The standard intake could be replaced with any 80mm pipe for the same effect as the AD pipe. Samco silicon pipe would be ideal and you would need no more than one 90 degree bend and one 45 degree bend and a small amount of straight length (plus joining fitments of course) and it should work out a little bit cheaper than Autodelta, although might not look as good as the carbon fibre. BTW, the AD carbon fibre build quality is a bit rough internally and the pipe is quite fragile too so you need to be gentle with it.
Its not really possible to see what part of the power increase is from increasing the pipe diameter against what detriment (if any) is gotten by removing the resonators. Certainly removing the resonators increases the noise considerably so if its just a good noise you are after then take them off. I can`t see that the smoothing of the power curve can be only through a pipe diameter increase so the resonators must be restrictive in some fashion. However without the full pipe replacement I doubt you will get the increase in throttle response.
The full pipe replacement is definately the ultimate winner though and I thoroughly recommend it. That distinctive 'V' engine noise is just irresistable. By 'eck does it sound good !