Quad ESL Cap mods


Hello,
I have a pair of Quad 988 I'm considering replacing the electrolytic 220uF Capacitor for a film cap...

For those who have done it -- what caps give you the clearest extensions in the highs and improved mids without mudding the low???

Also, who makes a 220uF film cap? All I seem to find is lower values? Is it best to wire a bunch of lower value caps together for a total 220uF (if so, should you mix electrolytic caps with film caps - like some modders do) or is it best to have a single 220uF cap?

I do see Mundorf has 200+uF caps in their Tube Cap line -- are these Mundorf Tube Caps appropriate for the Quad ESL application? how do they sound?

Thank you guys very much for any and all input into this, as I'm just beginning my Quad mod journey...
128x128grateful
Let me know how you want the information to be sent or posted, I have provided other forum members with more detailed information. I am not aware that the information can be uploaded to this forum. Newer Quad models after the 988/989 present more of a challenge because of their interior space, and have had more quality build issues.
I'm thinking of getting a pair of 2905s and really interested in this mod discussion. But a) i am rubbish with a soldering iron and b) don't fancy messing with the high voltages involved.
is there anyone in the UK that can provide an upgrade service along the lines of Plitron transformer substitution or caps swap etc ?
I use 2x 100 uF F&T bipolars + a 18 uF SCR MKP, FS2 shorted
You talk about a 1,5 uF cap in the 988/989, where is it located? The only 1,5 uF I find on the shematic is around the 555 chip. Surely you can't mean that one?