The bigger issue with the Simons header may not be quality; but, the fact that it is a 4:1 header. A 4:1 header will not improve the performance of most B20 engines unless they are approaching a race tune. Most B20 engines will do very well with the stock exhaust manifold as used on the B20E / F heads with the 4 into 2 design. It was Volo's standard fitment for most of the R performance packages for the B20. If you don't have access to an E or F manifold, Tinus Tuning and at least one other (can't remember the name) sell 4:2:1 designs.

As a side note, the IPD header was made by Patriot, not Simons (unless Simons outsources it from Patriot - unlikely). I think VP Autoparts (definitely not VPD) may list some 4:2:1 headers.

And yes, do not purchase from VPD. If you Google Vintage Performance Developments and customer complaints / customer reviews / scam / fraud you will get a pile of hits. John Parker is notorious for accepting orders on parts and once the order is processed, proceeding to a delaying tactic based on variations of 'waiting to ship because short xx of the pieces'. The objective is to wait out the Pay Pal dispute time limit at which point he stops responding to enquiries. If you are tempted to order from VPD make sure initiate the PayPal dispute resolution if you don't get immediate delivery. Even that does not always work. I know someone who shipped their head to Parker for a type II rebuild. The work took forever and what eventually came back definitely did not qualify as even a good basic rebuild.