Those 243 heads flow allot better than the 5.3 heads do. Run them but mill first to make up the compression

 

There is alot of info on the TBSS/NNBS intake swap. Just do a search. Many for sale also. This is just one: https://www.performancetrucks.net/fo...apters-501906/

 

im running a tr 220 cam with ported, polished 706 heads that were cc'd and milled .012 and im around 370hp...?

 

All the inform is great and I very grateful, another ideal I had, I have the LS performance book ,and I read that the 5.3 can be bore over to 99mm making it into a 5.7, the only problem that escapes me is where do you find the .030 dished pistons? I check many sites, with no result. If anybody knows something, please let me know, because this might be another route I may go.

 

You can bore it to the stock bore size of a LS1. You just order LS1 pistons, in whichever dish you need for your compression.

 

Great, I'm try to keep the comperssion around 9.5 to 9.8 without going to higher octane fuel. So with a decent cam, I'm pretty sure that this might be the quickest route to take and the least costly.