in my experience by far the best mod you can do for your car is the ARBs. i have coilovers, arbs, walk etc etc. ARBS made the biggest difference by a long shot.
also when lowering the car more important than the lowering height should be the dampers. I know lowering the vRS whilst maintaining standard dampers made for a fidgety ride, considering the two cars maintain the same underppinnings it would be the same on the Leon.
im not saying coilovers are the way forward, but pairing lowering springs to uprated dampers is a must.
The torque arm insert made the grand total of .........no noticable difference on mine.
instead i say look into an uprated lower subframe engine mount. your looking at £100 ish but you will nearly elliminate wheel hop, and remove the slop in the transmission slop.
my list would read
-front and rear anti roll bars
- Mk2 audi TT lower support arms(around £300) to give you an extra hal degree of negative camber
-WALK
-lower mount
that setup will make your car a completely differnt animal.
Anti roll bars will lose the body roll in the car,
The TT lower arms will give you phenominal amounts of extra grip in the corners whilst maintaining normal tyre wear,
The Walk will give you a stiffer feel on the steering and a better turn in (due to the extra half degree of caster)
The lower mount will massively reduce wheel hop, thus increasing traction.
only then would i be looking into uprated springs/dampers or coilovers.