First off, please forgive the quality & layout of this page. Making a stretch IC is a pretty labor intensive project that IMO, only a few people will be willing to undertake hence the need for quality pics and a lot of details wouldn't be needed. I purchased my CAS V-4 Intercooler at the 2000 GSCA Nationals but prior to that, I had already began making my own stretched IC by using 2 stock GN IC cores. I decided to use a 15 row configuration to maintain reasonable ground clearance in my GN.
Below are pictures of the sections after bandsawing them, the mock-up and the final product. I used a few pieces of the original tanks from the parts that weren't used to fabricate the side tanks and used 1/4" 2024 aluminum plate for other sections. The welding also included the installation of a Duttwieler neck.
The total welding cost was $100 and was done by a friend. The 2 ICs cost $150 and the Dutt neck was $70. I sold this IC to another friend and his GN has seen a minimum gain of 3/10 in the 1/4 mile since installing it.