I have been through this nightmare scenario and given up!
On an R34 (should be very similar) I was told they would fit and it looks possible but in order to get them in the rear windscreen has to be removed! As the company is question couldn't guarantee not breaking it and a replacement one being unavailable I gave up and retired to keeping the standard fits in place.
SOrry to be the bearer of bad news but maybe someone else has a better method?
You junk the plastic speaker mounts that are standard, and fabricate new ones for your 6x9's.
You use the standard speaker covers but need to move them slightly. It makes for a good stealthy install.
It can all be done by removing the back seats, no need to touch the rear screen.
No idea about R34.
I would first of all question what you are trying to achieve with 6*9's before trying to see if you can get them in.
in an ideal in car setup for music your best bet is a decent front component setup (3 way is the very best) and a sub. No rear speakers at all.
rear speakers tend to just drag the soundstage backwards.
however if you don't want to go the sub route but still want a decent amount of bass then 6*9s can be very good at providing this - although I would recomend that you cut the tweeters out and just use them purely for mid bass.
If that is what you are aiming for but the 6*9s won't go in then you could perhaps look at a set of 5" focal subs wheich would get the same result.
Had the same probs myself. As ever it depends on how far you want to go.
Audiofile in Bishops Stortford who set up my system recommended abandoning the 6x9 idea as the magnets were going to be too deep and going for a smaller set of infinity rears,with the front setup being infinity base units in the existing door panel plus tweeters in the top of the panel. This is powered by a Genesis amp under the carpet in the boot. Using a Sony MD head unit the sound quality is excellent.
I took the view that if you are running anything other than a standard car with a standard exhaust then going mad with a top end sound system would add very little to the final in-car sound plus the car remains almost standard inside.
I just installed a pair of Infinity 6x9's into the rear shelf of my R32, used the standard speaker covers, so looks totally standard... this is the method that I used...
removed the old speakers and amp, I bought some MDF spacers, 10mm deep...
removed the rear seat... 2 bolts and slide it up and out...
removed the carpeted section of the shelf... 2 plastic clips and a row of metal clips by the window...
now climb into the boot... there should be a depression in each of the holes that the original speakers came out of, this will sit inside the spacer... (the speaker cone WONT touch this, even on full travel) drill throught the spacer and shelf, bolt the spacer to the underside of the shelf... screw the speaker to the spacer...
on the right hand side the Hicas control unit will be in the way, cut the spacer to fit around this, this speaker will sit about 10mm further to the right... but you shoul;dnt really hear the difference.
The power cable for the amp runs from the battery, under the sill covers, under rear quarterpanel covers the bottom of the seat and into the boot throught the same hole that the seatbelts go through... make sure the cable doesnt interfere with the seatbelts here... (5m power will get from the batt, to the rear wheel) i put a distribution block here, and ran the powercable along behind the rear seat to the amp, the phonos run the same way along the other side of the car...
hope that helps!!!
Ive always used 6x9's and a sub, along with components up front, usually pwered with 3 amps... may sound like overkill, but it sounds very good.. full control over the whole tonal range...
I fitted infinity kappa 5" woofers in the rear perfect fit and gives good bass as would a larger woofer, but space in the boot is small as we all know so that killed 2 birds with one stone. Gives very good bass i find.
Max did your car come fitted with the infinity components up front. Because mine has, just wondering if I'm not the only one. How do they sound when ampped???
Also to everyone who has replied, my car has been fitted with Sony 6.5" 3 way speakers on the rear shelf, so I don't have the original speaker covers. And yeah I'm definitely getting comps upfront whether it be the std. Infinitys or something else.
GU51 8OY if you mount them from below, won't that make them even lower and nearer to the batt/ecu bracket???
And yeah don't really won't to put a sub in the boot. Just want quality system that doesn't have to be LOUD, LOUD.