Hola :-)
I can see, you guys are going on with installation. All of you are right, the IL 135 (now 155) is a problem in the mustang. it is a little bit to high (if you dont want to see the engine commin out downside)
The IL150 fits as it is. no special parts needed. hope everyone of you get the parts you need, if not you can contact me, i will help you as good as possible.
If someone here is reading all this, i want to say something about Mustang and Engine:
If you want a Badass engine and dont care about the price use a IL150
If you want a perfect fitting engine with cool sound fo less money, use a IL100. i had this engine in my BF109, 100 inch and 21 Kilos and it was still powerful enough. i have a video of that in my youtube channel where you can see the performance of the "Smaller" 2zylinder.
less wheight and stress ;-)
for sure IL135 is also good, but a little bit more difficult to install, and the new IL155 is 3mm higher i think .
greets
Tom