From the bus station of Kashgar we take a bus (4 seater taxi for 33 CNY/person) towards Ulugqat. This was a Sunday (close border).
We wanted to sleep in Ulugqat that night, so on Monday morning in the early morning do the long Chinese border procedures.
In the police control 3 Km before arriving in the city, they held us for 2 hours. Many questions. They checked in all corners of our backpacks, including mobiles, camera and computer. They tried to install some program in the Android but they did not get anything.
After that time, they told us that we could not sleep in Ulugqat. They proposed us to return to Kashgar but we refused.
Finally, they took us to a hotel next to the border control, near an industrial zone, 3 Km from Ulugqat. We had no choice. They isolated us. We paid 80 CNY/night/room with three beds and a private bathroom.
There is nothing to buy, just four stores and a restaurant. Evidently, we were accompanied by the police and their patrol car in the work of looking for food. Very kind and friendly.
The next day, in the morning, they came to look for us at the hostel and accompanied us to the border control gate. It took us 3 hours to get the exit stamp from China. They did not check our backpacks but they asked a lot of questions and they reviewed the camera and mobile phones again.
Finally, exit stamp and we rode in the taxi (100 CNY/person) that took us to the last Chinese border control. Previously we passed a couple of simple controls more. The buffer zone China is all militarized are about 180 Km.
Once in no man's land, we walk 1 Km to Kyrgyz territory where a military passport checks you. From this point to the custom there are 3 Km. We went walking but some Chinese asked the military for a taxi, he called and a taxi came to look for them. We do not know price.
With a Spanish passport, easy and fast border control in Kyrgyzstan, we not need visa and were even welcomed. We were free!
To get out of Kyrgyzstan's custom, we recommend hitchhiking to Sary Tash. Taxis ask for 100 CNY/person from Irkestam to Sary Tash, but it is achieved in half. There is place to sleep in Irkestam. In Sary Tash there is only one cashier who accepts Visa and does not charge commission. At the gas station of Sary Tash they change money easily.
Thanks to China for the border experience never lived, and for the landscapes Absolutely incredible!

We hope our experience helps other travelers.
Regards,
Alberto and Sonia