Gotcha! Well based on this info the reducers I got might just do the trick and I won't have to worry about physically fixing them onto the end of the exhaust pipes! I can just used them as cheap funnels and they will direct the gases more accurately towards the trims and won't melt the glue!
Owe you a beer mate thanks very much!
If your ever in the north east of Scotland I'll hold you to that haha,
3"-2.5" reducer should be perfect tbh as you've seen the Renault ones are a bit oversize typical French overcompensation