I am doing some research about street racing.  I am posting five
questions on the subject, and paying five dollars per question
answered...

1.  What kind of cars are better for street racing, tuners or muscle cars?

2.  What size of cam will give the most horsepower for your money?

3.  How can you add horsepower to any car?

4.  What are the best street racing tires?

5.  If you want to put a normal Toyota Corrolla with a 1.6 engine into
street racing, what should you do to enhance its performance..without
changing the engine.

it all depends what type of street racing you want to do imports
handle well muscle cars have plenty of horse power .i would go for a a
light 4wd import like a   nissan pulsar gtr or a lotus elise we have a
car over in the uk that will see off most high out put cars its called
a ariel atom it has a honda type r engine that puts out 240 bhp will
do 0-100 in under 10 secs

Hi, 

 These are great questions and you should look into cams that will
give you the most BHP per cylinder but also the strongest possible
hold.  I had a GTR that blew through 3 sets of cams with the setup I
was running.  For straight up racing, i hate to say itm but mustangs
are awesome for straight racing.  For a more subtle and sleek
approach, a lotus is sweet, but will cost you a boatload too.  A
performance enhanced mustang is easy, safe, and will usually knock
your socks off.   Check this website out for info on tuning cars. 
http://www.carperform.com/cgi-bin/index.pl?=&=G6H1Are

I agree with what they are saying, but it also depends on what type of
driver you are. True, Mustangs are great on the straight, but I seen
350Z TT and a Mitsubishi Eclipse GSX burn Mustangs all day on the
strip. Then there is a Mazda Miata with a V-8 block that burns tha
strip in the mid to low 9's. So it all depends how much time you have
and your funding. - Optimum Motorworks