i just read an article about porting the stock L98 exhaust manifolds my ? is is it worth it? will it make the car sound better since i allready have a flowmaster exhaust? how much gain would i get?

 

It won't sound any different. It can help flow, though not nearly as much as headers.

I have a bud who did all sorts of things to his ZZ3 crate engine, all emissions-legal, but kept stock manifolds (with dual cats and Loudmouth cat-back). He ran low 14's here, which translates to low 13's at sea level. He still plans on headers, though.

I know another racer who has a 383 with roots blower in a 37 Chevy pickup. He uses ported rams horn manifolds. Late last season, the passenger side broke off at the flange - too thin to take the weight of the exhaust pipe under the abuse of racing. He said he was going to find another one and port it this winter - we'll see. Oh, did I mention he was season track champion in two different classes last year?

 

But what would he be running with headers

 

TBD. He has an old-style set of SLP 1-5/8", he wanted to port match them, trial fit, then have them coated. He has fibramyalgia (sp?), so can't sustain manual activity for more than an hour or so in a day. They moved to Fort Worth in November, so will probably get some sea level runs as-is before he does the headers. Of course, now he's talking about getting 1-3/4" SLPs and putting the ones he has now on his wife's GTA...