So I was able to purchase famous used GRS intercool V1 from UK forum for 250 pounds. Here are the pics comparing to stock jcw intercooler.

 

JCW ic is nothing different than any r52/r53 ic. Only GP ic is what works best. Airtec and GRS still do not beat GP ic. You should have just bought meth to work with your Stock IC for a better result

 

Yes, true that gp ic is the best but from tests posted on here while back this one is little more efficient from stock and for the price you can't beat it. I really want to add meth in the future.

 

any of the new ebay intercoolers have better designs yet? at least more fins and the nice tapered edge into the core?

I'm still surprised none of them beat the GP intercooler

 

Before on stock intercooler on hot days after a 20 min city drive to work was hot too touch. now with Grs I can easily touch the the outlet side and the diff between in and out changed greatly. So I know is working. I did my reaserch on all uk forums. Grs and airtec are most popular right after 1k £ gp ic. https://www.northamericanmotoring.co...ing-tests.html