Anyone ever bought one of these cheap sport cats from ebay?

For that money you can buy a 3" DP and sports cat... the std cats are not the restriction its the crappy downpipe... so to answer your question... most people just buy a 3" DP and sports or de cat

<tuffty/>
 
An improvement over stock if keeping below 'stage 2' spec?

I believe JoJo noticed an improvement when running a decat with standard DP.
 
nope
jojo's car was faster because his wallet was lighter
no real gains to be had here
throttle response maybe
 
Cheers for the replies guys,

I was more referring to whether they fit ok, as im planning in getting a milltek cat back but the milltek sports cat and downpipe is just so expensive!!!!

and then go to a stage 2
 
stage 2 with no dp?
get a relentless