Crackdown

(Update 5th Sept 2013 - Note: I am currently working on getting the times for each race.)

(Update 24th March 2014 - Managed to go through all the races in the game and get the times to beat. They have been added to each race in the list.)

List taken from: http://www.gamefaqs.com/xbox360/930144-crackdown/faqs/47211

Although all of the guides here keep going on about the insane difficulty of the Alleys of the Den race, they do not say where each race is located. I have therefore looked elsewhere online and found a complete list of the location of each race. As an added bonus, the list I found gave a few helpful tips for some of the races.

I have also included a YouTube video link of the Alleys of the Den race being completed with the Agency Supercar. (Note: Not my video so credit goes to DuvalAK47 for creating and posting it online). Also note that the time to beat in the video is 1:32, this is incorrect as this is DuvalAK47's personal best. The correct time to beat is 1:40 and, as the video shows, there is room for error so don't be discouraged if you make some mistakes like the video shows.

As UnrealKazu points out in the comments, you can use the Agency Race Car to make things easier however, this is a DLC car from the Getting Busy Bonus Pack.

Also note that a trophy should pop up on the screen if you have beaten the specific time. If the trophy does not appear on screen, then you must do the race again (By trophy, I mean an actual trophy, not Playstation trophies).

Race locations are as follows:

1. Hillside High
Location: Los Muertos, northern island.
From Nearest Supply Point: A short trip northeast from Garcia Point.
It's by Diaz's racetrack.
Time To Beat: 5:30:00

2. La Mugre Alleys
Location: Los Muertos, southern island.
From Nearest Supply Point: It's a short trip north of Hillside Housing.
Time To Beat: 1:40:00

3. Tour the Den
Location: Volk, southern island
From Nearest Supply Point: Go south from the Retreat supply point.
Time To Beat: 1:30:00

4. The Freeway Gauntlet
Location: Volk, southern island
From Nearest Supply Point: Head west from the Storage Facility supply point.
Time To Beat: 5:20:00

5. The Alleys of the Den
Location: Volk, southern island
From Nearest Supply Point: Head north up the road at Maxim's Arch.
You'll see the race on your radar for sure. Also, I'm declaring this to be the most fucking evil race in the game. Lots of small tunnels, no room for error, and an insanely short time to run it. You'll probably go through this race a damn lot, since you pretty much need a perfect run to pull it off. Best of luck, and do try not to shoot yourself in the head out of frustration.
Time To Beat: 1:40:00

6. Shai-Gen Shopper's
Location: Shai-Gen, western island
From Nearest Supply Point: This one's south of the Bubble supply point.
Bring your SUV to this one, as there's lots of stairs to go up and down in the beginning. Also, don't be afraid to run over people. It'll be impossible to not do so in this race, so might as well go all out, right?
Time To Beat: 1:45:00

7. City Park Burnout
Location: Shai-Gen, northern island
From Nearest Supply Point: A quick stop north of the Comfortitude, LTD. supply point. It's right next to the only pond in the park.
Time To Beat: 1:50:00

8. Shai-Gen Tourist
Location: Shai-Gen, southern island
From Nearest Supply Point: It's a small trip west from the Intellicenter. Definitely bring the Supercar.
Time To Beat: 3:35:00

9. Crazy Horse
Location: Los Muertos, southern island
From Nearest Supply Point: This race is just a little southeast of the Hillside Housing supply point.
Time To Beat: 1:55:00

10. The Volk Endurance Test
Location: Volk, northern island
From Nearest Supply Point: It's across the bridge from the Hi-Power Tower supply point.
Time To Beat: 7:50:00

11. The Los Muertos Endurance Test
Location: Los Muertos, southern island
From Nearest Supply Point: Head north from the Pacific City Bank supply point.
Time To Beat: 6:50:00

12. The Widowmaker
Location: Volk, northern island
From Nearest Supply Point: Go up the bridge by the Hi-Power Tower, and take a left. The race is down the road; you'll see it.
Time To Beat: 1:40:00

13. Off-Road Chaos
Location: Los Muertos, northern island
From Nearest Supply Point: It's right by Garcia Point. Can't miss it.
Time To Beat: 2:40:00

14. La Mugre Coast
Location: Los Muertos, southern island
From Nearest Supply Point: It'll show up on your radar when you emerge from the Royal Vista supply point. The race is behind Guerra's nightclub.
Time To Beat: 1:30:00

If you're still having problems with "Alleys of the Den" there's another way which I personally found to be easier.
You need to have the premium DLC (the one that costs MS points) or have a friend who does that can host the game.
Then simply use the Agency Race Car as it is small enough to fit through all the tight spots, but also has very good brakes, handling and acceleration.
I was able to do it first try this way, even with a few bad mistakes.

The most well known solution is that you can use a ramp truck placed in front of the tricky bollard section to make sure you can easily get this achievement.

Alternatively, as a extra note: you can get through the bollards in the supercar in "Alleys of the Den" without relying on luck or the ramp truck (with level 4 driving as well). If you aim for the gap just to the right of the centre bollards you can squeeze through. The other gaps aren't wide enough.

This makes the rest of the race pretty simple once you learn the route. Also, towards the end you can squeeze to the right of the metal columns whilst accelerating flat out in the supercar by continually steering to the right against the railings. That can save a couple of seconds.

The only other issue is the jump towards the start, but if you pull up on the analogue stick to point the car in the air you can easily get over the ledge.

One solution to "Alleys of the Den" which I found to be the easiest for me: This goes back to the method for the street races trick on using the supercar.

Go back to the agency and grab yourself a supercar. Now drive the supercar to where the pylons are and park it on the other side, within the alley. Leave it there and go grab yourself either the agency peacemaker, or a coupe (they get more airtime for the first ramp, they also fit between the pylons.) Now start the race and once you fly through the pylons, hop out and into your supercar who has been waiting for you, finish the race - easy. I think my finish time was around 1:22-1:24.

If anyone is still tring to do the Alleys of the Den. I have found it a lot easier with the Peacekeeper race car. Smaller for all gaps, quicker on short distances,lots easier with pylons etc. First try 1:26.