BLOX Racing is proud to offer its Performance DIY product line for today’s growing Do-It-Yourself fabricator.  Whether you are just learning to fabricate and weld or you are a seasoned veteran, BLOX Racing can supply your needs. The BLOX Racing merge collectors are a perfect choice of fabricators when building a custom exhaust header or turbo exhaust manifold. Small and large sizes are available in welded and non-welded units. Box Merge Collector Specs Length: 3" (small) / 5" (large) ID:  1.7" Wall thickness: 0.1" (small) / 0.07" (large) Schedule 10